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Maintaining or Reducing Large Jpg to 8 Bit

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Currently I work with images that start at 5000 x 5000 pixels (52.09 x 52.09 inches), at 96 dpi and a bit depth of 32. When I save to a TIFF in Paint.NET, I get a file that is ~ 3 million bytes. When I save the same image as a JPEG with a bit depth of 24 (at 95% compression) it is half that size. When I save it as a PNG with a bit depth of 8 it is about the same file size as the JPEG. If you need to have a small JPEG file size you will have to increase the compression to ~ 50%. When I save the same file as a 50% compression JPEG, I got the file size down to ~ 0.5 million bytes.

Is there some reason that the bit depth must be 8? If you need a bit depth of 8; you may want to save the file as a GIF.

(The Paint.NET JPEG compression is defaulted at 95%). Remember to set it back if you are going to do other projects during the same session. I will often just close out one session and start a new project in PDN rather than restarting.

Also, JPEG file compression is a lossy file format! Each time a JPEG is open re-worked and saved again, you run the risk of losing image data to each iteration.

As I attempt to live up to the name of "HyReZ", I shoot all of my photos as RAW and convert copies to various file formats depending upon the project or purpose.


Edited by HyReZ
Correcting spelling and adding more nfo!


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Greetings Mike Mc,

I had forgotten about the best freeware image file conversion software around.
IranView by Irfan Skiljan, can convert to an 8 bit color depth gray-scale JPEG
When you save as a JPEG make sure that the gray-scale box is checked. That's it!


You can also save in batch mode and do all of your image files in one operation!

Edited by HyReZ
inserting additional information
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