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Hello,
I’ve been using PS for a long time but not a graphics pro… I was working on a very simple image the other day and noticed that when I changed color modes (from CMYK to RBG and back to CMYK) the size of the GIF image (using "Save for Web…" feature) dramatically increases every time I change image modes:
Original image in CMYK…
Image Mode: CMYK
Image Width: 183px
Image Height: 488px
Image Res: 135px/in
Pixel Dimensions: 349 Kb
Image Size (using "Save for Web…" option): 3.195 Kb (GIF, 16 Col, 88% dither, selective palette, optimized)
Change Image Mode to RGB…
Image Mode: RGB
Image Width: 183px
Image Height: 488px
Image Res: 135px/in
Pixel Dimensions: 262 Kb
Image Size (using "Save for Web…" option): 16.67 Kb (GIF, 16 Col, 88% dither, selective palette, optimized)
Change Image Mode back to CMYK…
Image Mode: CMYK
Image Width: 183px
Image Height: 488px
Image Res: 135px/in
Pixel Dimensions: 349 Kb
Image Size (using "Save for Web…" option): 25.13 Kb (GIF, 16 Col, 88% dither, selective palette, optimized)
I am guessing that this has something to do with PS adapting color palettes as you switch from one mode to another, thereby increasing the range of colors. If I am on the right track, then I still don’t understand the big difference in image sizes bcs all 3 images are saved as GIFs using a selective palette of only 16 colors. Can someone explain what PS is doing here?
Thank you.
Mike
I’ve been using PS for a long time but not a graphics pro… I was working on a very simple image the other day and noticed that when I changed color modes (from CMYK to RBG and back to CMYK) the size of the GIF image (using "Save for Web…" feature) dramatically increases every time I change image modes:
Original image in CMYK…
Image Mode: CMYK
Image Width: 183px
Image Height: 488px
Image Res: 135px/in
Pixel Dimensions: 349 Kb
Image Size (using "Save for Web…" option): 3.195 Kb (GIF, 16 Col, 88% dither, selective palette, optimized)
Change Image Mode to RGB…
Image Mode: RGB
Image Width: 183px
Image Height: 488px
Image Res: 135px/in
Pixel Dimensions: 262 Kb
Image Size (using "Save for Web…" option): 16.67 Kb (GIF, 16 Col, 88% dither, selective palette, optimized)
Change Image Mode back to CMYK…
Image Mode: CMYK
Image Width: 183px
Image Height: 488px
Image Res: 135px/in
Pixel Dimensions: 349 Kb
Image Size (using "Save for Web…" option): 25.13 Kb (GIF, 16 Col, 88% dither, selective palette, optimized)
I am guessing that this has something to do with PS adapting color palettes as you switch from one mode to another, thereby increasing the range of colors. If I am on the right track, then I still don’t understand the big difference in image sizes bcs all 3 images are saved as GIFs using a selective palette of only 16 colors. Can someone explain what PS is doing here?
Thank you.
Mike
How to Master Sharpening in Photoshop
Give your photos a professional finish with sharpening in Photoshop. Learn to enhance details, create contrast, and prepare your images for print, web, and social media.
