Hi,

I've been using GNU/Linux for many years, and am finally taking steps to reduce Windows to a gaming platform only. One important category is photography. I've used the GIMP a lot and have been quietly browsing several photo apps for various tasks; they've really progressed in recent years. There is almost too much choice!

On Windows I used XnView as my image viewer and for simple manipulations, but for batch JPG resizing I found Irfanview hard to beat. It has an intuitive interface for options, of which the following have become musts:

• resize longest side, maintaining aspect ratio
• specify the exact number of pixels
• select a useful algorithm (usually cubic)
• set JPG compression
• process subdirectories recursively
• write processed files to a new location, preserving subdirectory structure
• confirm error-free operation or list errors

A nice-to-have is visual feedback of progress during processing.

Up till now, the main purpose of this has been to downsize the ~3MB JPG images my digital camera makes for fast viewing—viewing images 640 pixels max side length instead of 3504 pixels, I can browse more efficiently, and watch my life in fast-forward, so to speak. So now I am moving everything to be done on Debian, and want to downsize my 80-GB collection to an intermediate resolution for my wife to work with. I'd like her to use a photo management app instead of doing everything by hand. I could of course use Irfanview for the job and then copy everything to a *nix partition, but that's sort of not the point.

I know the heavily promoted Imagemagick can do batch conversion efficiently and is used as a backend for a lot of apps, but I'm not sure whether it can preserve subdirectory structure; this is a must because of over 200 subdirectories. The mogrify command changes the original image, and it seems inefficient to copy 80 GB only to downsize it. I'm sure that read-resize-write can be done preserving directory structure by using a script, and I'd be willing to do that in the future, but for now I lack experience and am not willing to use a script I don't understand. So to anyone suggesting this route I'd ask for help understanding the script.

Otherwise, there seem to be few free apps that do batch resizing with the features above. I looked into Phatch, but it doesn't seem to let me set the exact resolution I want. I don't want to use Picasa until Google makes it free. Gwenview does batch resize, but doesn't seem to give all the options, unless I missed something.

Any other choices on this task?
Thanks

michapma,
you might check out digikam I think it uses KDE libs, but; I use it in Gnome. I have not had much time to really explore its options yet, Digikam has received some good reviews. I also looked at is bibble and lightzone,they both cost money,but; they may have a free trial period. That is my limited knowledge

Hey thanks highfructose, digikam does have image manipulation capability. However, it is a photo management app—to do anything with it at all I had to tell it several settings preferences, like where I want to store images. To me this is overkill for just batch resizing images, and after checking out the menus and help, nothing is mentioned; google says it can be done for imported images with a plug-in. So this is not the idea way to my taste.

For photo management, right now I think it's down to digikam or f-spot. digikam looks feature-rich and has nice documentation. f-spot looks great except that it forces you to import any images it works with; this might work out with the downsized jpgs (downsize, import then delete the import source to prevent having double image sizes). I was excited about blueMarine, but it doesn't look stable enough yet.

bibble and lightzone do look interesting, as does pixel image editor, but I'm planning to stick with free software; free meaning freedom, which also IrfanView is not.

So thanks, but I'm still looking for a batch-resize program...

In the meantime I tried Phatch, because I found out it does support entering the exact dimensions and pretty much everything on my list. Unfortunately, it aborted upon execution after processing only one file. I filed a bug.

I'm still looking for a solution!

You touched on ImageMagick, but there was no further discussion. Have you tried it?

michapma,
here is a interesting plug-in for GIMP that does batch resizing, you have got me curious about this. My wife just switched to Linux full time from Apple and she is a Professional Photographer. She wants to give Open Source a go and I am sure batch resizing will come up at some point. I found the link for the plug-in at this post in the Ubuntu forums they discuss a few other options like a Nautilus plug-in to do batch resizing. The GIMP plug-in looked good because it talked about keeping the aspect ratio correct when scaling the image.

GIMP---and I would hope any other photo SW---will always maintain the aspect ratio by default. Also, I assume the plugin is using the GIMP scaling functions and not adding something different

pixellany, yeah I would hope so too. As you said I am sure the plug-in is expanding GIMP's native functions. I was responding to the OP's first item on their list I can imagine some very simple software either cropping or stretching and image to fit a predefined template size, I would guess that is the concern

I have a hard time imagining any simple and/or automated process that makes the cropping decisions. How can the SW know what part of the picture is to be discarded?

pixellany, it seems crazy but JS PhotoPrep list auto crop as a feature how many peoples head would get cut off ?

I suppose they might be mis-using the word "crop". Regardless, I will probably always crop by hand---there is no substitute for the subjective decision on the composition of the picture.