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-   -   thumbnail sizes (http://www.photobanter.com/showthread.php?t=131076)

Phillip Helbig[_2_] January 7th 18 09:07 PM

thumbnail sizes
 
I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done

Files from the K10D result in thumbnails of about 57 kB and those from
the GR of about 46 kB, with little variation. Is there a simple
explanation as to why?

The K10D is 10 megapixels and the GR 16, but I don't see why that is
relevant here, but maybe I am missing something.


Mayayana January 7th 18 09:46 PM

thumbnail sizes
 
"Phillip Helbig (undress to reply)" wrote

| I've been using this to make thumbnails of jpeg files:
|
| for img in *.JPG; do
| echo thumbnailing $img
| convert -geometry 105x70 $img $img
| done
|

Are people supposed to know what OS/software
you're using that code with?

I wonder why you don't just extract the thumbnails
when possible. Don't your cameras create them in
the JPGs? It should be quicker and yield better
quality images.



Carlos E.R. January 7th 18 10:01 PM

thumbnail sizes
 
On 2018-01-07 21:46, Mayayana wrote:
"Phillip Helbig (undress to reply)" wrote

| I've been using this to make thumbnails of jpeg files:
|
| for img in *.JPG; do
| echo thumbnailing $img
| convert -geometry 105x70 $img $img
| done
|

Are people supposed to know what OS/software
you're using that code with?


Linux/bash and ImageMagick, obviously :-P


I wonder why you don't just extract the thumbnails
when possible. Don't your cameras create them in
the JPGs? It should be quicker and yield better
quality images.


To customize the size and quality, for instance.


--
Cheers, Carlos.

Carlos E.R. January 7th 18 10:03 PM

thumbnail sizes
 
On 2018-01-07 21:07, Phillip Helbig (undress to reply) wrote:
I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done

Files from the K10D result in thumbnails of about 57 kB and those from
the GR of about 46 kB, with little variation. Is there a simple
explanation as to why?

The K10D is 10 megapixels and the GR 16, but I don't see why that is
relevant here, but maybe I am missing something.


I was going to say that the camera with more megapixels would convert to
a bigger size, but the reverse is happening.

--
Cheers, Carlos.

Savageduck[_3_] January 7th 18 10:22 PM

thumbnail sizes
 
On Jan 7, 2018, Phillip Helbig (undress to reply wrote
(in article ):

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done


Why?
Why not use decent software?

Files from the K10D result in thumbnails of about 57 kB and those from
the GR of about 46 kB, with little variation. Is there a simple
explanation as to why?


Different cameras, different image content.

The K10D is 10 megapixels and the GR 16, but I don't see why that is
relevant here, but maybe I am missing something.


The RAW file size, and native JPEG size is going to be different for those
two cameras. As a result any thumbnail from those different sources is going
to have a different size.

I am still curious as to why you need to generate thumbnails. It seems to be
a pointless exercise.

--

Regards,
Savageduck


Savageduck[_3_] January 7th 18 10:26 PM

thumbnail sizes
 
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-07 21:46, Mayayana wrote:
"Phillip Helbig (undress to wrote

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done


Are people supposed to know what OS/software
you're using that code with?


Linux/bash and ImageMagick, obviously :-P


That figures.

I wonder why you don't just extract the thumbnails
when possible. Don't your cameras create them in
the JPGs? It should be quicker and yield better
quality images.


To customize the size and quality, for instance.


Quality for thumbnails?
To what purpose?
It seems to be a waste of time, and a futile, unnecessary exercise.

--

Regards,
Savageduck


Mayayana January 7th 18 11:17 PM

thumbnail sizes
 
"Carlos E.R." wrote

| I was going to say that the camera with more megapixels would convert to
| a bigger size, but the reverse is happening.
|

MP doesn't matter because it's the same
number of pixels in the thumbnail if they're
both the same width/height. There could be
slight differences due to simpler or more complex
images that compress differently, but with such
a big difference the only explanation I can
think of is that there's a difference in the
compression. The code doesn't include a
"quality" parameter to set compression level
so maybe ImageMagick is deciding based on
input size? Who knows? He's using a hammer
to hit a tack.

It's hard to see why it should matter. He's
using a limited command line tool to get
thumbnails and not even setting the quality
option. Does he really need exactly that size?
If so, why? Is it worth sacrificing quality?
He didn't explain any of that. Apparently he
doesn't care very much about the quality but
is just curious about the different file sizes
resulting.




Mayayana January 7th 18 11:30 PM

thumbnail sizes
 
"Phillip Helbig (undress to reply)" wrote

| I've been using this to make thumbnails of jpeg files:
|
| for img in *.JPG; do
| echo thumbnailing $img
| convert -geometry 105x70 $img $img
| done
|
| Files from the K10D result in thumbnails of about 57 kB and those from
| the GR of about 46 kB, with little variation. Is there a simple
| explanation as to why?
|
| The K10D is 10 megapixels and the GR 16, but I don't see why that is
| relevant here, but maybe I am missing something.
|

Are the originals the same aspect ratio?
If not then you might be getting something
like a 105x65 and a 105x50. You also didn't
spec the compression level with the quality
parameter. (Assuming you're using ImageMagick
as Carlos speculated.)

You didn't say what the context of the code
is. You didn't say why you're making thumbnails
or whether they need to be the same size. You
didn't extract them, which would probably make
more sense. So all we know is that you're making
thumbnails with a poorly suited tool and you don't
much care about the quality of them. But you
do care about the file size? Why?

It'd be easier for people to provide a helpful
answer if you'd explain yourself. We're not your
mother.



Carlos E.R. January 8th 18 02:33 AM

thumbnail sizes
 
On 2018-01-07 22:26, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-07 21:46, Mayayana wrote:
"Phillip Helbig (undress to wrote

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done

Are people supposed to know what OS/software
you're using that code with?


Linux/bash and ImageMagick, obviously :-P


That figures.

I wonder why you don't just extract the thumbnails
when possible. Don't your cameras create them in
the JPGs? It should be quicker and yield better
quality images.


To customize the size and quality, for instance.


Quality for thumbnails?
To what purpose?
It seems to be a waste of time, and a futile, unnecessary exercise.


No. I said "to customize the size and quality" which is different than
doing a quality thumbnail. ie, to have thumbnails of the exact quality
(small quality) that one wishes.

--
Cheers, Carlos.

Carlos E.R. January 8th 18 02:39 AM

thumbnail sizes
 
On 2018-01-07 22:22, Savageduck wrote:
On Jan 7, 2018, Phillip Helbig (undress to reply wrote
(in article ):

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done


Why?
Why not use decent software?


"convert" is very decent and powerful software.
What would you use in a script, then?

--
Cheers, Carlos.

Carlos E.R. January 8th 18 02:57 AM

thumbnail sizes
 
On 2018-01-07 23:30, Mayayana wrote:
"Phillip Helbig (undress to reply)" wrote

| I've been using this to make thumbnails of jpeg files:
|
| for img in *.JPG; do
| echo thumbnailing $img
| convert -geometry 105x70 $img $img
| done
|
| Files from the K10D result in thumbnails of about 57 kB and those from
| the GR of about 46 kB, with little variation. Is there a simple
| explanation as to why?
|
| The K10D is 10 megapixels and the GR 16, but I don't see why that is
| relevant here, but maybe I am missing something.
|

Are the originals the same aspect ratio?
If not then you might be getting something
like a 105x65 and a 105x50. You also didn't
spec the compression level with the quality
parameter. (Assuming you're using ImageMagick
as Carlos speculated.)


Oh, I'm more than 95% certain :-)


You didn't say what the context of the code
is. You didn't say why you're making thumbnails
or whether they need to be the same size.


I rather suppose he is curious about why they are not about the same
size, if the pixel number is the same.

But it does not matter to me why is he making them. Not my business :-)

You
didn't extract them, which would probably make
more sense. So all we know is that you're making
thumbnails with a poorly suited tool and you don't


It is a perfectly suited tool for this task (a repeated task in a script).

much care about the quality of them. But you
do care about the file size? Why?


Then use the -quality parameter, to make sure it is the same on all
runs. With no value given, the program tries to estimate the value used
in the original and use the same (see
http://www.imagemagick.org/script/co...s.php#quality).

It'd be easier for people to provide a helpful
answer if you'd explain yourself. We're not your
mother.


Sigh... Maybe he doesn't know what other information to provide, and
you can simply politely ask for what you think you need :-)


--
Cheers, Carlos.

Savageduck[_3_] January 8th 18 03:14 AM

thumbnail sizes
 
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-07 22:26, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-07 21:46, Mayayana wrote:
"Phillip Helbig (undress to
wrote

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done

Are people supposed to know what OS/software
you're using that code with?

Linux/bash and ImageMagick, obviously :-P


That figures.

I wonder why you don't just extract the thumbnails
when possible. Don't your cameras create them in
the JPGs? It should be quicker and yield better
quality images.

To customize the size and quality, for instance.


Quality for thumbnails?
To what purpose?
It seems to be a waste of time, and a futile, unnecessary exercise.


No. I said "to customize the size and quality" which is different than
doing a quality thumbnail. ie, to have thumbnails of the exact quality
(small quality) that one wishes.


I am still baffled as why these thumbnails have to be produced in the first
place. A proof/contact sheet, some sort of project, what?

If there is some odd reason to produce them, which has yet to be explained,
why would the concept of “quality” be attached to thumbnails of all
things?

I have been doing this digital photography thing for some time, and I have
yet to have the need to produce a thumbnail of any quality.

--

Regards,
Savageduck


Savageduck[_3_] January 8th 18 03:17 AM

thumbnail sizes
 
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-07 22:22, Savageduck wrote:
On Jan 7, 2018, Phillip Helbig (undress to reply wrote
(in article ):

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done


Why?
Why not use decent software?


"convert" is very decent and powerful software.
What would you use in a script, then?


Why use “convert” which I have never heard of when I have Lightroom,
Bridge, and a few others in my photgraphic tool box?

--

Regards,
Savageduck


Carlos E.R. January 8th 18 03:43 AM

thumbnail sizes
 
On 2018-01-08 03:14, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):



I wonder why you don't just extract the thumbnails
when possible. Don't your cameras create them in
the JPGs? It should be quicker and yield better
quality images.

To customize the size and quality, for instance.

Quality for thumbnails?
To what purpose?
It seems to be a waste of time, and a futile, unnecessary exercise.


No. I said "to customize the size and quality" which is different than
doing a quality thumbnail. ie, to have thumbnails of the exact quality
(small quality) that one wishes.


I am still baffled as why these thumbnails have to be produced in the first
place. A proof/contact sheet, some sort of project, what?


Does it matter?

If there is some odd reason to produce them, which has yet to be explained,
why would the concept of “quality” be attached to thumbnails of all
things?

I have been doing this digital photography thing for some time, and I have
yet to have the need to produce a thumbnail of any quality.


Yes, you do. Any JPG generation has a "quality". It can be "one", so
very bad, or it can be "a hundred", so as best as can be, or any number
in between. Any jpg generated or changed has a quality number. You
choose the number, or you let the software decide.

Having a quality does not mean having high quality.


--
Cheers, Carlos.

nospam January 8th 18 03:49 AM

thumbnail sizes
 
In article , Mayayana
wrote:


| I've been using this to make thumbnails of jpeg files:
|
| for img in *.JPG; do
| echo thumbnailing $img
| convert -geometry 105x70 $img $img
| done
|

Are people supposed to know what OS/software
you're using that code with?


yes

I wonder why you don't just extract the thumbnails
when possible. Don't your cameras create them in
the JPGs? It should be quicker and yield better
quality images.


maybe he wants a different size.

nospam January 8th 18 03:49 AM

thumbnail sizes
 
In article , Carlos E.R.
wrote:


I am still baffled as why these thumbnails have to be produced in the first
place. A proof/contact sheet, some sort of project, what?


Does it matter?


yes.

If there is some odd reason to produce them, which has yet to be explained,
why would the concept of quality be attached to thumbnails of all
things?

I have been doing this digital photography thing for some time, and I have
yet to have the need to produce a thumbnail of any quality.


Yes, you do. Any JPG generation has a "quality". It can be "one", so
very bad, or it can be "a hundred", so as best as can be, or any number
in between. Any jpg generated or changed has a quality number. You
choose the number, or you let the software decide.


that doesn't answer the question.

nospam January 8th 18 03:49 AM

thumbnail sizes
 
In article , Carlos E.R.
wrote:

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done


Why?
Why not use decent software?


"convert" is very decent and powerful software.
What would you use in a script, then?


there's no need to use a script at all. why make things more difficult
than they need to be?

Savageduck[_3_] January 8th 18 03:56 AM

thumbnail sizes
 
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-08 03:14, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in ):


I wonder why you don't just extract the thumbnails
when possible. Don't your cameras create them in
the JPGs? It should be quicker and yield better
quality images.

To customize the size and quality, for instance.

Quality for thumbnails?
To what purpose?
It seems to be a waste of time, and a futile, unnecessary exercise.

No. I said "to customize the size and quality" which is different than
doing a quality thumbnail. ie, to have thumbnails of the exact quality
(small quality) that one wishes.


I am still baffled as why these thumbnails have to be produced in the first
place. A proof/contact sheet, some sort of project, what?


Does it matter?

If there is some odd reason to produce them, which has yet to be explained,
why would the concept of “quality” be attached to thumbnails of all
things?

I have been doing this digital photography thing for some time, and I have
yet to have the need to produce a thumbnail of any quality.


Yes, you do. Any JPG generation has a "quality". It can be "one", so
very bad, or it can be "a hundred", so as best as can be, or any number
in between. Any jpg generated or changed has a quality number. You
choose the number, or you let the software decide.

Having a quality does not mean having high quality.


....er, OK. It seems we are talking at cross purposes. While I have produced
many JPEGs, I have not gone out of my way to deliberately produce thumbnails.

--

Regards,
Savageduck


Carlos E.R. January 8th 18 03:59 AM

thumbnail sizes
 
On 2018-01-08 03:17, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-07 22:22, Savageduck wrote:
On Jan 7, 2018, Phillip Helbig (undress to reply wrote
(in article ):

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done

Why?
Why not use decent software?


"convert" is very decent and powerful software.
What would you use in a script, then?


Why use “convert” which I have never heard of when I have Lightroom,
Bridge, and a few others in my photgraphic tool box?


Because it is a tool designed for scripts and other repetitive tasks.
Most Linux users doing image handling will be familiar with it, but you
also have it in Windows, and is used by other tools in the back without
telling you.

https://en.wikipedia.org/wiki/ImageMagick


The tiny code excerpt from the OP would process an entire directory in
one click. Or one "enter". As you can see in the documentation,
"convert" has dozens of possible options, several pages:

http://imagemagick.org/script/convert.php

There are also many examples of use. For instance, there is one
"-thumbnail":

https://www.imagemagick.org/Usage/resize/#thumbnail


A whole chapter of it:

https://www.imagemagick.org/Usage/thumbnails/


And it has some information that may explain what is happening to the OP:

«Many images from digital cameras, scanning software, and some paint
programs (photoshop is notorious for this), save extra information about
the image in the form of profiles. This includes image formats such a
JPEG, PNG, TIFF and as of IM v6.2.4-1 GIF. Of course the IM specific
format, MIFF also does this. (See Image Profiles for more detailed
information).»

«These profiles can be up to 60 Kb in size, so can make a big difference
to your file size, and by default IM will preserve this profile
information. Thumbnails have no need for this data and often not even
the main image needs it.»


--
Cheers, Carlos.

Carlos E.R. January 8th 18 04:01 AM

thumbnail sizes
 
On 2018-01-08 03:49, nospam wrote:
In article , Carlos E.R.
wrote:

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done

Why?
Why not use decent software?


"convert" is very decent and powerful software.
What would you use in a script, then?


there's no need to use a script at all. why make things more difficult
than they need to be?


Scripts are trivial to use for automation. What, you do not know...? Wow.

--
Cheers, Carlos.

Carlos E.R. January 8th 18 04:02 AM

thumbnail sizes
 
On 2018-01-08 03:49, nospam wrote:
In article , Carlos E.R.
wrote:


I am still baffled as why these thumbnails have to be produced in the first
place. A proof/contact sheet, some sort of project, what?


Does it matter?


yes.


No.


If there is some odd reason to produce them, which has yet to be explained,
why would the concept of ³quality² be attached to thumbnails of all
things?

I have been doing this digital photography thing for some time, and I have
yet to have the need to produce a thumbnail of any quality.


Yes, you do. Any JPG generation has a "quality". It can be "one", so
very bad, or it can be "a hundred", so as best as can be, or any number
in between. Any jpg generated or changed has a quality number. You
choose the number, or you let the software decide.


that doesn't answer the question.


Yes.

--
Cheers, Carlos.

nospam January 8th 18 04:03 AM

thumbnail sizes
 
In article , Carlos E.R.
wrote:

The tiny code excerpt from the OP would process an entire directory in
one click.


so will other apps, *without* needing to write a script.

nospam January 8th 18 04:11 AM

thumbnail sizes
 
In article , Carlos E.R.
wrote:


"convert" is very decent and powerful software.
What would you use in a script, then?


there's no need to use a script at all. why make things more difficult
than they need to be?


Scripts are trivial to use for automation. What, you do not know...? Wow.


wow what? i know what a script is. the point is there is no need for
one when existing apps *already* can do it.

Savageduck[_3_] January 8th 18 04:12 AM

thumbnail sizes
 
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-08 03:17, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-07 22:22, Savageduck wrote:
On Jan 7, 2018, Phillip Helbig (undress to reply wrote
(in article ):

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done

Why?
Why not use decent software?

"convert" is very decent and powerful software.
What would you use in a script, then?


Why use “convert” which I have never heard of when I have Lightroom,
Bridge, and a few others in my photgraphic tool box?


Because it is a tool designed for scripts and other repetitive tasks.
Most Linux users doing image handling will be familiar with it, but you
also have it in Windows, and is used by other tools in the back without
telling you.

https://en.wikipedia.org/wiki/ImageMagick


Interesting. However, I do not use Linux, or Windows, or ImageMagick.

The tiny code excerpt from the OP would process an entire directory in
one click. Or one "enter". As you can see in the documentation,
"convert" has dozens of possible options, several pages:

http://imagemagick.org/script/convert.php


Did I say that I do not use ImageMagick?

I have all sorts of tools I can use (including scripts) for various types of
bulk processing.

There are also many examples of use. For instance, there is one
"-thumbnail":

https://www.imagemagick.org/Usage/resize/#thumbnail

A whole chapter of it:

https://www.imagemagick.org/Usage/thumbnails/


....and in my opinion, all of that appears to be a royal PIA.

And it has some information that may explain what is happening to the OP:

«Many images from digital cameras, scanning software, and some paint
programs (photoshop is notorious for this), save extra information about
the image in the form of profiles. This includes image formats such a
JPEG, PNG, TIFF and as of IM v6.2.4-1 GIF. Of course the IM specific
format, MIFF also does this. (See Image Profiles for more detailed
information).»

«These profiles can be up to 60 Kb in size, so can make a big difference
to your file size, and by default IM will preserve this profile
information. Thumbnails have no need for this data and often not even
the main image needs it.»


....but why the need for thumbnails in the first place, or have I missed
something?

--

Regards,
Savageduck


Mayayana January 8th 18 04:13 AM

thumbnail sizes
 
"Carlos E.R." wrote

| It'd be easier for people to provide a helpful
| answer if you'd explain yourself. We're not your
| mother.
|
| Sigh... Maybe he doesn't know what other information to provide, and
| you can simply politely ask for what you think you need :-)
|

And apparently he also can't speak for himself.
Maybe *you're* his mother. :)



Carlos E.R. January 8th 18 04:13 AM

thumbnail sizes
 
On 2018-01-08 04:03, nospam wrote:
In article , Carlos E.R.
wrote:

The tiny code excerpt from the OP would process an entire directory in
one click.


so will other apps, *without* needing to write a script.


But having to navigate several menus to set the options right.

--
Cheers, Carlos.

nospam January 8th 18 04:15 AM

thumbnail sizes
 
In article .com,
Savageduck wrote:

There are also many examples of use. For instance, there is one
"-thumbnail":

https://www.imagemagick.org/Usage/resize/#thumbnail

A whole chapter of it:

https://www.imagemagick.org/Usage/thumbnails/


...and in my opinion, all of that appears to be a royal PIA.


exactly.


And it has some information that may explain what is happening to the OP:

Many images from digital cameras, scanning software, and some paint
programs (photoshop is notorious for this), save extra information about
the image in the form of profiles. This includes image formats such a
JPEG, PNG, TIFF and as of IM v6.2.4-1 GIF. Of course the IM specific
format, MIFF also does this. (See Image Profiles for more detailed
information).

These profiles can be up to 60 Kb in size, so can make a big difference
to your file size, and by default IM will preserve this profile
information. Thumbnails have no need for this data and often not even
the main image needs it.


...but why the need for thumbnails in the first place, or have I missed
something?


still unanswered.

Carlos E.R. January 8th 18 04:19 AM

thumbnail sizes
 
On 2018-01-08 03:56, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-08 03:14, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in ):



I have been doing this digital photography thing for some time, and I have
yet to have the need to produce a thumbnail of any quality.


Yes, you do. Any JPG generation has a "quality". It can be "one", so
very bad, or it can be "a hundred", so as best as can be, or any number
in between. Any jpg generated or changed has a quality number. You
choose the number, or you let the software decide.

Having a quality does not mean having high quality.


...er, OK. It seems we are talking at cross purposes. While I have produced
many JPEGs, I have not gone out of my way to deliberately produce thumbnails.


Me neither, but some people do :-)

Maybe he wants to have a directory that loads and browses fast with
small versions of the photos. Who knows?

For instance, somebody I knew generated them in order to create a web
page on his home server. The user would see a bunch of photos, click on
one and get the large version. So he wanted to generate much smaller
versions to optimize load time for the preview.

Yeah, sure, there will be some product out there that does it all. Where
is the joy in it, instead of doing it yourself completely? Or maybe he
was creating one of those "products" :-P

--
Cheers, Carlos.

nospam January 8th 18 04:23 AM

thumbnail sizes
 
In article , Carlos E.R.
wrote:


The tiny code excerpt from the OP would process an entire directory in
one click.


so will other apps, *without* needing to write a script.


But having to navigate several menus to set the options right.


not at all, but even if that were true, it would be much easier than
writing (and debugging) a script to do what is *already* built in. not
only that, but those apps can also be scripted.

nospam January 8th 18 04:23 AM

thumbnail sizes
 
In article , Carlos E.R.
wrote:


...er, OK. It seems we are talking at cross purposes. While I have produced
many JPEGs, I have not gone out of my way to deliberately produce
thumbnails.


Me neither, but some people do :-)

Maybe he wants to have a directory that loads and browses fast with
small versions of the photos. Who knows?


no point in that when apps do that far better, faster and with far more
flexibility.

For instance, somebody I knew generated them in order to create a web
page on his home server. The user would see a bunch of photos, click on
one and get the large version. So he wanted to generate much smaller
versions to optimize load time for the preview.


couple of clicks to export a webpage that does that (and more).

Yeah, sure, there will be some product out there that does it all. Where
is the joy in it, instead of doing it yourself completely? Or maybe he
was creating one of those "products" :-P


if you like making more work for yourself, go for it.

it's the linux way.

Carlos E.R. January 8th 18 04:24 AM

thumbnail sizes
 
On 2018-01-08 04:12, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-08 03:17, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-07 22:22, Savageduck wrote:
On Jan 7, 2018, Phillip Helbig (undress to reply wrote
(in article ):

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done

Why?
Why not use decent software?

"convert" is very decent and powerful software.
What would you use in a script, then?

Why use “convert” which I have never heard of when I have Lightroom,
Bridge, and a few others in my photgraphic tool box?


Because it is a tool designed for scripts and other repetitive tasks.
Most Linux users doing image handling will be familiar with it, but you
also have it in Windows, and is used by other tools in the back without
telling you.

https://en.wikipedia.org/wiki/ImageMagick


Interesting. However, I do not use Linux, or Windows, or ImageMagick.


But the OP is using Linux :-)

Can you help him?

I don't criticize people for using Windows or whatever. Why have some
people got to criticize people for their choices?


The tiny code excerpt from the OP would process an entire directory in
one click. Or one "enter". As you can see in the documentation,
"convert" has dozens of possible options, several pages:

http://imagemagick.org/script/convert.php


Did I say that I do not use ImageMagick?


Then don't post, perhaps? :-P


I have all sorts of tools I can use (including scripts) for various types of
bulk processing.

There are also many examples of use. For instance, there is one
"-thumbnail":

https://www.imagemagick.org/Usage/resize/#thumbnail

A whole chapter of it:

https://www.imagemagick.org/Usage/thumbnails/


...and in my opinion, all of that appears to be a royal PIA.


Everybody is entitled to his opinion :-)


And it has some information that may explain what is happening to the OP:

«Many images from digital cameras, scanning software, and some paint
programs (photoshop is notorious for this), save extra information about
the image in the form of profiles. This includes image formats such a
JPEG, PNG, TIFF and as of IM v6.2.4-1 GIF. Of course the IM specific
format, MIFF also does this. (See Image Profiles for more detailed
information).»

«These profiles can be up to 60 Kb in size, so can make a big difference
to your file size, and by default IM will preserve this profile
information. Thumbnails have no need for this data and often not even
the main image needs it.»


...but why the need for thumbnails in the first place, or have I missed
something?


Why does it matter? It doesn't to me, at all.

--
Cheers, Carlos.

Carlos E.R. January 8th 18 04:25 AM

thumbnail sizes
 
On 2018-01-08 04:23, nospam wrote:
In article , Carlos E.R.
wrote:


The tiny code excerpt from the OP would process an entire directory in
one click.

so will other apps, *without* needing to write a script.


But having to navigate several menus to set the options right.


not at all, but even if that were true, it would be much easier than
writing (and debugging) a script to do what is *already* built in. not
only that, but those apps can also be scripted.


Yeah, sure :-P

--
Cheers, Carlos.

Carlos E.R. January 8th 18 04:25 AM

thumbnail sizes
 
On 2018-01-08 04:23, nospam wrote:
In article , Carlos E.R.
wrote:


...er, OK. It seems we are talking at cross purposes. While I have produced
many JPEGs, I have not gone out of my way to deliberately produce
thumbnails.


Me neither, but some people do :-)

Maybe he wants to have a directory that loads and browses fast with
small versions of the photos. Who knows?


no point in that when apps do that far better, faster and with far more
flexibility.

For instance, somebody I knew generated them in order to create a web
page on his home server. The user would see a bunch of photos, click on
one and get the large version. So he wanted to generate much smaller
versions to optimize load time for the preview.


couple of clicks to export a webpage that does that (and more).

Yeah, sure, there will be some product out there that does it all. Where
is the joy in it, instead of doing it yourself completely? Or maybe he
was creating one of those "products" :-P


if you like making more work for yourself, go for it.

it's the linux way.


Have fun your way, then! :-P



--
Cheers, Carlos.

Carlos E.R. January 8th 18 04:27 AM

thumbnail sizes
 
On 2018-01-08 04:11, nospam wrote:
In article , Carlos E.R.
wrote:


"convert" is very decent and powerful software.
What would you use in a script, then?

there's no need to use a script at all. why make things more difficult
than they need to be?


Scripts are trivial to use for automation. What, you do not know...? Wow.


wow what? i know what a script is. the point is there is no need for
one when existing apps *already* can do it.


Ok, I'll bite. Which one?
In Linux, of course. You know all. :-P

--
Cheers, Carlos.

nospam January 8th 18 04:42 AM

thumbnail sizes
 
In article , Carlos E.R.
wrote:


"convert" is very decent and powerful software.
What would you use in a script, then?

there's no need to use a script at all. why make things more difficult
than they need to be?

Scripts are trivial to use for automation. What, you do not know...? Wow.


wow what? i know what a script is. the point is there is no need for
one when existing apps *already* can do it.


Ok, I'll bite. Which one?


lightroom and photos both can export photos in whatever sizes the user
wants. plenty others.

there is also no need to generate separate thumbnails anyway. it's a
manufactured problem.

In Linux, of course. You know all. :-P


no, not in linux.

linux has the least amount of available software and most of what does
exist for linux isn't particularly good.

that's why you have to resort to writing scripts to do basic tasks such
as exporting photos.

nospam January 8th 18 04:42 AM

thumbnail sizes
 
In article , Carlos E.R.
wrote:


The tiny code excerpt from the OP would process an entire directory in
one click.

so will other apps, *without* needing to write a script.

But having to navigate several menus to set the options right.


not at all, but even if that were true, it would be much easier than
writing (and debugging) a script to do what is *already* built in. not
only that, but those apps can also be scripted.


Yeah, sure :-P


it's true.

Savageduck[_3_] January 8th 18 05:02 AM

thumbnail sizes
 
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-08 04:12, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-08 03:17, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote
(in article ):

On 2018-01-07 22:22, Savageduck wrote:
On Jan 7, 2018, Phillip Helbig (undress to reply wrote
(in article ):

I've been using this to make thumbnails of jpeg files:

for img in *.JPG; do
echo thumbnailing $img
convert -geometry 105x70 $img $img
done

Why?
Why not use decent software?

"convert" is very decent and powerful software.
What would you use in a script, then?

Why use “convert” which I have never heard of when I have Lightroom,
Bridge, and a few others in my photgraphic tool box?

Because it is a tool designed for scripts and other repetitive tasks.
Most Linux users doing image handling will be familiar with it, but you
also have it in Windows, and is used by other tools in the back without
telling you.

https://en.wikipedia.org/wiki/ImageMagick


Interesting. However, I do not use Linux, or Windows, or ImageMagick.


But the OP is using Linux :-)


For the task he has in mind, an unfortunate choice.

Can you help him?


Since he hasn’t responded to any of our questions yet, probably not. Unless
of course you are his self-appointed spokesperson.

I don't criticize people for using Windows or whatever.


Neither do I. Feel free to use Linux, Windows, macOS. However, there is one
of those which is not a good choice for phographic work.

Why have some people got to criticize people for their choices?


So far in this thread there has been no criticism for any choice of OS.
However, don’t take offence when it is pointed out that perhaps a
particular choice for a specific job is a bad one.

The tiny code excerpt from the OP would process an entire directory in
one click. Or one "enter". As you can see in the documentation,
"convert" has dozens of possible options, several pages:

http://imagemagick.org/script/convert.php


Did I say that I do not use ImageMagick?


Then don't post, perhaps? :-P


The OP, Phillip said nothing about ImageMagick, you did. He said that he was
using a script to make thumbnails.


I have all sorts of tools I can use (including scripts) for various types of
bulk processing.

There are also many examples of use. For instance, there is one
"-thumbnail":

https://www.imagemagick.org/Usage/resize/#thumbnail

A whole chapter of it:

https://www.imagemagick.org/Usage/thumbnails/


...and in my opinion, all of that appears to be a royal PIA.


Everybody is entitled to his opinion :-)


Well, you have mine.

And it has some information that may explain what is happening to the OP:

«Many images from digital cameras, scanning software, and some paint
programs (photoshop is notorious for this), save extra information about
the image in the form of profiles. This includes image formats such a
JPEG, PNG, TIFF and as of IM v6.2.4-1 GIF. Of course the IM specific
format, MIFF also does this. (See Image Profiles for more detailed
information).»

«These profiles can be up to 60 Kb in size, so can make a big difference
to your file size, and by default IM will preserve this profile
information. Thumbnails have no need for this data and often not even
the main image needs it.»


...but why the need for thumbnails in the first place, or have I missed
something?


Why does it matter? It doesn't to me, at all.


However, there is something pointless about the idea.

--

Regards,
Savageduck


Mayayana January 8th 18 03:09 PM

thumbnail sizes
 
"Savageduck" wrote

| Can you help him?
|
| Since he hasn't responded to any of our questions yet, probably not.
Unless
| of course you are his self-appointed spokesperson.

Maybe Carlos and Phillip are 2 aliases for the
marketing person at ImageMagick. That would
explain a lot. Phillip asked what seems to be an
unimportant question in an almost childish way,
with no context, and then checked out. While
Carlos uses every post to sing the praises of
ImageMagick.

I've looked into ImageMagick before as a
possible programming tool for graphics operations.
I've never seen the sense of it. As a resource for
programming it's very clunky and indirect, having
no value in actual usage because the operations
are all inside. A programmer is a cook. ImageMagick
is a waiter's order window. You tell it what you
want. It loads an image, does that operation,
then resaves the image.

As a command-line tool.... A vast collection
of graphic editing functions that only work from
the command line? Only Linux people could
think that makes sense. Here's an example of
drawing a line across an image, from their drawing
tutorial:

convert rose: -fill none -stroke white -draw 'line 5,40 65,5' rose_raw.png

How do you know the coordinates to draw from/to
without a GUI? You don't, of course. Then that
one operation has to resave the image. It's
nonsensical.

But I suppose he has
a point in a very limited context: If you only
have Linux and if you don't have any tool to
do batch thumbnail production... and that's what
you want to do... and you don't mind spending a
couple of hours learning commandline incantations...
and you don't much care about the quality of
the thumbnails... then ImageMagick might be a
very good choice. It could also be handy for similar,
simple batch tasks like resizing hundreds of images.
But on Windows (and no doubt on Mac) there are
plenty of options for things like that.



Savageduck[_3_] January 8th 18 04:00 PM

thumbnail sizes
 
On Jan 8, 2018, Mayayana wrote
(in article ):

wrote

Can you help him?


Since he hasn't responded to any of our questions yet, probably not.

Unless
of course you are his self-appointed spokesperson.


Maybe Carlos and Phillip are 2 aliases for the
marketing person at ImageMagick. That would
explain a lot. Phillip asked what seems to be an
unimportant question in an almost childish way,
with no context, and then checked out. While
Carlos uses every post to sing the praises of
ImageMagick.

I've looked into ImageMagick before as a
possible programming tool for graphics operations.
I've never seen the sense of it. As a resource for
programming it's very clunky and indirect, having
no value in actual usage because the operations
are all inside. A programmer is a cook. ImageMagick
is a waiter's order window. You tell it what you
want. It loads an image, does that operation,
then resaves the image.

As a command-line tool.... A vast collection
of graphic editing functions that only work from
the command line? Only Linux people could
think that makes sense. Here's an example of
drawing a line across an image, from their drawing
tutorial:

convert rose: -fill none -stroke white -draw 'line 5,40 65,5' rose_raw.png

How do you know the coordinates to draw from/to
without a GUI? You don't, of course. Then that
one operation has to resave the image. It's
nonsensical.

But I suppose he has
a point in a very limited context: If you only
have Linux and if you don't have any tool to
do batch thumbnail production... and that's what
you want to do... and you don't mind spending a
couple of hours learning commandline incantations...
and you don't much care about the quality of
the thumbnails... then ImageMagick might be a
very good choice. It could also be handy for similar,
simple batch tasks like resizing hundreds of images.
But on Windows (and no doubt on Mac) there are
plenty of options for things like that.


I agree.

While Linux has a place in the computing spectrum, it is not the most
sensible choice for most folks when it comes to doing anything productive
with photography, or graphics. There is a reason that the great majority of
photography, and graphics software is only written for, and supported by WIN,
and/or macOS.

At this point in this thread I would have expectedthat we would have heard
from Floyd Davidson to challenge that assertion. I am surprised that he
hasn’t as he has been the champion of Linux, and GIMP in this NG.
Floyd, like many of us in this NG is no youngster, so I hope that he is in
good health up there above the Arctic Circle in Barrow. Regardless of his
support of all things Linux, Floyd is knowledgeable with regard to many
photography, and technology related things, and would probably have had an
answer that Carlos would have approved of.

--

Regards,
Savageduck


nospam January 8th 18 04:02 PM

thumbnail sizes
 
In article , Mayayana
wrote:


But I suppose he has
a point in a very limited context: If you only
have Linux and if you don't have any tool to
do batch thumbnail production...


welcome to linux.

and that's what
you want to do... and you don't mind spending a
couple of hours learning commandline incantations...
and you don't much care about the quality of
the thumbnails... then ImageMagick might be a
very good choice.


yep.

It could also be handy for similar,
simple batch tasks like resizing hundreds of images.
But on Windows (and no doubt on Mac) there are
plenty of options for things like that.


yep.


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