More on digital photo compression on Ubuntu Linux.

Ok… I was looking over my last post and it looks like I was coming off a bad week…. This week seems better but I’ve got some things piling up on my gtd list that I’ve been wanting to get done.

I’ve been taking some pictures of some shop projects that I’ve been wanting to post on my blog.  But they are just way to big.

I’ve had this thread bookmarked for a long time and just haven’t had the time to really go through it:

From what I gather to reduce file size of a picture you can:

  • Reduce the image size
  • Reduce the number of colors
  • Save in a different format

That seems fairly self evident.
Well… lets see what I got here..
I have a series of really pretty pictures of my counter-shaft base of my ammco shaper. Err… starting to get off OT here.. Lets just say, I just have this nice picture buts its big.

I fired up the GIMP (I’m sorry put I can’t help but keep thinking of Pulp Fiction when I write that)and went to Image properties.  Its a JPEG 2272 X 1740 pixels, print size 31.556 X 23.667 Inches, Resolution 72 X 72 ppi, 831 KB.
I did a quick google search “gimp how is print size calculated” and came up with link

First experiment. Take Image save as Png (compression level 9).
Lets see what I got.  Hmm.. Everything else is the same… file size just shot up to 5.26Mb..

Second experiment.  I just tried Image=>Scale and changed the image scale to 640X480. When I saved as Jpeg it asked me about quality.. I selected 50%. Seemed like a reasonable number. (File size was 40.1 Kb) That’s better.
Let me try that again with maximum quality and see what happens. at Maximum Quality it shoots up to 309.7 KB (picture seems nicer but file size is not that great

I just tried Image mode indexing and save at 85% quality with web colors enabled.  Looks like crap.  Saved as Jpeg at original Original image scale.  File size at 821KB…

Another experiment. I changed to 640 X 480 saved as Png max compression. 536.8 KB

Ok… It’s seems for me at the moment, the best result I came up with using the Gimp, was 640X480 resolution and saved with 50% qc.  I reduced the file size from 831.7 Kb to 40.1 KB.. This seems reasonable..
For now, I’m just going to do this one at a time.  The post had some methods for doing this in batch mode.

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