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ondoho

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Registered: 2013-04-30

Posts: 692

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[Solved] Lossless JPG Cropping?

I'm looking for a simple tool to crop and flip/rotate jpg or jpeg images losslessly.

Most probably some sort of jpegtran frontend.

It can be command line, but a simple gui would be nice.
Another feature I want would be overwriting the original.

jpegtran itself would require 3 commands for every image: it doesn't get the logic right when I crop AND flip, so I need to do that in 2 commands, and then i need to force move the new file back onto the original.

I have investigated this, and came up with (and discarded):

- cropgui and cropgtk (I cannot enter a fixed ratio. It's very hard to drag the selection pixel-precise, and it changes by a few pixels every time I move it. It doesn't have flip/rotate. It doesn't overwrite originals)

- ljcrop (would seem to suit my needs but hopelessly outdated? I actually managed to find the file here but it's not running, missing the Tcl Img package)

- viewnior is simple and has all the functions but i cannot get any information on how it performs cropping/flipping/rotating and whether it is lossless)

I have tried a few more, mostly from this list.

Last edited by ondoho (2014-04-26 19:19:50)

sekret

Member

Registered: 2013-07-22

Posts: 308

Re: [Solved] Lossless JPG Cropping?

You could write a simple shell script to do this job for you. Do you need help with that?

ondoho

Member

Registered: 2013-04-30

Posts: 692

Website

Re: [Solved] Lossless JPG Cropping?

The problem is that the crops and flips are not always the same; I need to crop an exact sized region, but it can be anywhere in the picture and sometimes i want to flip/rotate it, sometimes not.
It's not simple batch processing I'm talking about.
I'm sorry I didn't make that clear in my first post.

ondoho

Member

Registered: 2013-04-30

Posts: 692

Website

Re: [Solved] Lossless JPG Cropping?

jpegtran cropping has some limitations which i wasn't aware of (not pixel-precise).
cropgui/cropgtk as a jpegtran frontend seems to be the best lossless solution, but for my personal needs i'm back to lossy cropping (and preferably having the original images available).

viewnior performs lossy crops.

Chazza

Wiki Maintainer

Registered: 2013-06-02

Posts: 506

Re: [Solved] Lossless JPG Cropping?

Doesn't gimp have an option for lossless cropping?

ondoho

Member

Registered: 2013-04-30

Posts: 692

Website

Re: [Solved] Lossless JPG Cropping?

i'm still talking about lossless JPG cropping, even if i forgot to mention it.
anyhow, that's not how gimp works.
explanation.

but thanks nevertheless.

Last edited by ondoho (2014-04-26 15:09:36)

emeres

Member

Registered: 2013-10-08

Posts: 1,570

Re: [Solved] Lossless JPG Cropping?

What about running Jpegcrop with wine or any other of the windows software listed? (that list is long) Works fine for me, however it is an another frontend for jpegtran.

By the way, how do you determine there is lossless cropping? Technically you would have to compare bytes of the original and cropped section.

Last edited by emeres (2014-04-26 16:09:12)

ondoho

Member

Registered: 2013-04-30

Posts: 692

Website

Re: [Solved] Lossless JPG Cropping?

What about running Jpegcrop with wine or any other of the windows software listed? (that list is long) Works fine for me, however it is an another frontend for jpegtran.

Appreciated, but i'm not installing wine for that.

anyhow, i have done some reading on lossless jpeg crop/rotate, and there are some limitations that are set by jpeg's compression itself.
this kind of brings down my whole idea, because i need to crop areas of the exact same dimension out of many different jpg images, and that exactly is not possible losslessly. at least not pixel-precise.

otherwise, cropgui is a great tool.

By the way, how do you determine there is lossless cropping? Technically you would have to compare bytes of the original and cropped section.

i trust the documentation.
also, if the saved cropped files size is larger than the original, or i get an extra dialog asking what quality i want to use, my guess is it's not lossless.

i'm marking this solved now. should have probably done that earlier.