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  #21  
Old January 8th 18, 03:02 AM posted to rec.photo.digital
Carlos E.R.
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Posts: 109
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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.
  #22  
Old January 8th 18, 03:03 AM posted to rec.photo.digital
nospam
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Posts: 21,658
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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.
  #23  
Old January 8th 18, 03:11 AM posted to rec.photo.digital
nospam
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Posts: 21,658
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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.
  #24  
Old January 8th 18, 03:12 AM posted to rec.photo.digital
Savageduck[_3_]
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Posts: 15,382
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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

  #25  
Old January 8th 18, 03:13 AM posted to rec.photo.digital
Mayayana
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Posts: 1,505
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"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.


  #26  
Old January 8th 18, 03:13 AM posted to rec.photo.digital
Carlos E.R.
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Posts: 109
Default 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.
  #27  
Old January 8th 18, 03:15 AM posted to rec.photo.digital
nospam
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Posts: 21,658
Default 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.
  #28  
Old January 8th 18, 03:19 AM posted to rec.photo.digital
Carlos E.R.
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Posts: 109
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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.
  #29  
Old January 8th 18, 03:23 AM posted to rec.photo.digital
nospam
external usenet poster
 
Posts: 21,658
Default 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.
  #30  
Old January 8th 18, 03:23 AM posted to rec.photo.digital
nospam
external usenet poster
 
Posts: 21,658
Default 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.
 




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