Linux - SoftwareThis forum is for Software issues.
Having a problem installing a new program? Want to know which application is best for the job? Post your question in this forum.
Notices
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here! Whether you are a digital nomad or just looking for flexibility, Shells can put your Linux machine on the device that you want to use.
Exclusive for LQ members, get up to 45% off per month. Click here for more info.
Which GUI tool is best for compressing image files in a batch?
I scan a lot of text documents that I want to post-process to deliver good quality printouts that can be copied (scan > print the scan > copy the print), while not consuming huge amounts of disc space.
I am not talking about resizing, but compressing while preserving original resolution, and I want to achieve the best possible balance between file size and readability of the scanned documents.
I scan DIN-A4-format sheets to jpeg format in 600 dpi res, which usually gives me files between 1,5 and 3,5 MB in size. Getting these down to 0,5 MB or below would be great.
There are several basic image editing and management applications that have compression options, but the outcome varies a lot, and usually there is no option to do batch jobs.
E.g. Libreoffice Draw has a feature for exporting to jpeg. With jpeg compression set to 100, it turns a 3,7MB file into 325KB. That's cool, but readability suffers too much (also, you can't batch process in LO). GIMP has an extension that makes a few tools available for batch processing, but not compression.
On the other hand, there are tools like Phatch, where compression set to e.g. 50 will give me pretty much half the file size - which is still too big.
I don't understand the logic: one reduces size to about a tenth when set to 100%, the other to a half when set to 50% (where the latter makes more sense mathematically, but the outcome is less desirable).
The ideal would be to have a little less compression than what LO does, where file size would still be ok, but with less of a penalty on readability - but 100% is already the least possible compression! How does this work?
For the ultimate in compression and readability how about using OCR software on the high resolution originals and then archive (or if you are happy with the results delete) them. Eg http://jocr.sourceforge.net/
Thanks. I don't suppose you'd like to give me the exact imagemagick commands? Because otherwise, GUI is the best way for me to do it. I have to use some kind of GUI tool in any case, because the scans also need to be cropped.
All the free OCR tools I have tried so far (including GOCR) give subpar results. All the powerful enough OCR software I have seen is commercial, and, more irritatingly, Windows only. Also the kind of documents I scan is not just text, but with images, charts etc and complex layout. That means, even if the OCR gets the text right enough, more post-processing is required, and that's a show-stopper for me.
Anyway thanks for your suggestions, but something along the lines of what I asked would be awesome.
just use imagemagick's "mogrify" program to convert them to lossless png's
Code:
mogrify png *.tif
that should be it , but i normally do not use IM much in the last few years
double check the png and tiff might need to be flipped
" mogrify *.tiff png " ????
All the free OCR tools I have tried so far (including GOCR) give subpar results. All the powerful enough OCR software I have seen is commercial, and, more irritatingly, Windows only. Also the kind of documents I scan is not just text, but with images, charts etc and complex layout. That means, even if the OCR gets the text right enough, more post-processing is required, and that's a show-stopper for me.
Ok, seems like OCR is not for you.
Quote:
Originally Posted by bennypr0fane
Anyway thanks for your suggestions, but something along the lines of what I asked would be awesome.
LinuxQuestions.org is looking for people interested in writing
Editorials, Articles, Reviews, and more. If you'd like to contribute
content, let us know.