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.