I am trying to optimize an animated GIF image in Photoshop. The current size is 2.2 MB. Following the guides I found online, they told me to "Save as Web" and then decrease the colors from 256 down to 128 or 64.

I tried that — however, when I try to decrease it, the size actually increased.

  • 128 colors = 4.4 MB
  • 64 colors = 5 MB

Does anyone know why this is happening?

Original (256 colors):


After (128 colors):

enter image description here

  • Can you upload a screenshot of your settings or describe them? It isn't normal behavior with defaults. Commented Aug 9, 2013 at 4:27
  • Sure, this is the original image: i.imgur.com/EhxvLb2.png This is the image after changing color to 128: i.imgur.com/lz9UyGZ.png
    – user81008
    Commented Aug 9, 2013 at 4:45
  • I have also tried to turn off diffuse but it doesn't really make a difference.
    – user81008
    Commented Aug 9, 2013 at 4:46
  • One thing I notice-- and I don't know what it means, is that the image on the top is different from the image on the bottom slightly. Commented Aug 9, 2013 at 4:55
  • He's just painting out the image for privacy. Caught my eye at first too: "where are all those colors being used?" ;) Commented Aug 9, 2013 at 6:04

2 Answers 2


Fewer colors + 100% dither + no Transparency Dither = greater size.

Adding a transparency dither or reducing the color dithering to less than 100% will most likely reduce the file size.

When you reduce the color table and have a high dither setting, you ask Photoshop to dither with fewer colors. This actually creates more color data to maintain from frame to frame, thus increasing the file size. The fact that your animation has 157 frames with 100% dithering it wouldn't surprise me if the file size quadrupled due to the dithering setting.

If you are truly interested in reducing the file size, you need to prune at least half those frames. This is especially true if image changes between the frames are present for all 157 frames. You simply can't squeeze a blue whale into a tuna can.

  • I just want to reduce it to below 2 mb so that I can upload it online. I tried to reduce the dithering to 0, and set a transparency dither but the size decreased by like 0.05 mb. I guess I'll take a look at reducing the number of frames.
    – user81008
    Commented Aug 9, 2013 at 11:59
  • 0% dithering can increase file size the same as 100% dithering can. Try odd percentages.. 43%, 64%, etc. Another option is to try the "Optimize to file size" in the Save for web window preferences. Then see what gets changed when you allow Save for Web to optimize the image.
    – Scott
    Commented Aug 9, 2013 at 12:17
  • Dithering, itself, sounds like a problem. Gotta watch out for people who dither around. Commented Aug 10, 2013 at 7:10
  • 2 megabytes is still a fat animated GIF. Commented Feb 4, 2016 at 12:41

Generally speaking, use either dither or color table reduction, but not both.

I recommend you use the Lossy slider. You have it set at zero. You can crank it up. The higher you go, the more information Photoshop will throw away as it converts your image into a GIF, and the smaller the file size will get.

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