How to convert to 4-bit grayscale for Kindle displays?

[abacus971]

Hello; I am editing an eBook for an author in Kindle format, and need some image formatting help. Perhaps some of you have seen the built-in screensaver images (like the image of Herman Melville) on a Kindle like the Kindle Keyboard model. If so, you know that they are capable of displaying stunning grayscale images, if pre-formatted correctly. However, if you simply try to display a color or grayscale photo on such a Kindle, they look terrible. Apparently, one key to making the images display well on the grayscale Kindles is to edit your image to match the 4-bit (16 levels of gray) grayscale palette in those Kindle models. According to some sources, the 16 grayscales that those models of Kindle can display correspond to: #ffffff or, 255 255 255 #eeeeee or, 238 238 238 #dddddd or, 221 221 221 #cccccc or, 204 204 204 #bbbbbb or, 187 187 187 #aaaaaa or, 170 170 170 #999999 or, 153 153 153 #888888 or, 136 136 136 #777777 or, 119 119 119 #666666 or, 102 102 102 #555555 or, 85 85 85 #444444 or, 68 58 68 #333333 or, 51 51 51 #222222 or, 34 34 34 #111111 or, 17 17 17 #000000 or, 0 0 0 The final image needs to be saved in a 4 bit (16 color) PNG-8 format with the above exact indexed values. Can someone outline the steps to do this in GC? In my case, I am starting with grayscale JPEG images, but I guess starting from color would just take a few extra steps before that. Thanks in advance. Larry

[thorstenlemke]

Hello Larry,ah - download the older version 7.6.2 for this.Open the file.Change the colors to grayscale 4 bit (16 colors).Save as PNG.The current version 8 does only support grayscale with 256 grays. Because it is completely rewritten in Cocoa for 64 bit support. Cocoa supports only 256 grays or more.Thorsten On 25.11.2012, at 22:25, "abacus971" <larryknight71@yahoo.com> wrote:   Hello; I am editing an eBook for an author in Kindle format, and need some image formatting help. Perhaps some of you have seen the built-in screensaver images (like the image of Herman Melville) on a Kindle like the Kindle Keyboard model. If so, you know that they are capable of displaying stunning grayscale images, if pre-formatted correctly. However, if you simply try to display a color or grayscale photo on such a Kindle, they look terrible. Apparently, one key to making the images display well on the grayscale Kindles is to edit your image to match the 4-bit (16 levels of gray) grayscale palette in those Kindle models. According to some sources, the 16 grayscales that those models of Kindle can display correspond to: #ffffff or, 255 255 255 #eeeeee or, 238 238 238 #dddddd or, 221 221 221 #cccccc or, 204 204 204 #bbbbbb or, 187 187 187 #aaaaaa or, 170 170 170 #999999 or, 153 153 153 #888888 or, 136 136 136 #777777 or, 119 119 119 #666666 or, 102 102 102 #555555 or, 85 85 85 #444444 or, 68 58 68 #333333 or, 51 51 51 #222222 or, 34 34 34 #111111 or, 17 17 17 #000000 or, 0 0 0 The final image needs to be saved in a 4 bit (16 color) PNG-8 format with the above exact indexed values. Can someone outline the steps to do this in GC? In my case, I am starting with grayscale JPEG images, but I guess starting from color would just take a few extra steps before that. Thanks in advance. Larry Reply via web post Reply to sender Reply to group Start a New Topic Messages in this topic (1)

[Carl von Einem]

That reminds me of the Psion display but I think that had only 4 grayscales. Neat. In GC v6.7.1 it's in menu Image: Colors: Grayscale: "16 Grayscales" Now just for fun test the grayscales with menu Image: Colors: "Edit Palette" and you will find it's the list of colors/grayscales you wrote down below. Don't save as JPG. GIF should work nicely. Carl abacus971 schrieb am 25.11.12 22:25: > Hello; > > I am editing an eBook for an author in Kindle format, and need some image formatting help. > > Perhaps some of you have seen the built-in screensaver images (like the image of Herman Melville) on a Kindle like the Kindle Keyboard model. If so, you know that they are capable of displaying stunning grayscale images, if pre-formatted correctly. > > However, if you simply try to display a color or grayscale photo on such a Kindle, they look terrible. > > Apparently, one key to making the images display well on the grayscale Kindles is to edit your image to match the 4-bit (16 levels of gray) grayscale palette in those Kindle models. > > According to some sources, the 16 grayscales that those models of Kindle can display correspond to: > > #ffffff or, 255 255 255 > #eeeeee or, 238 238 238 > #dddddd or, 221 221 221 > #cccccc or, 204 204 204 > #bbbbbb or, 187 187 187 > #aaaaaa or, 170 170 170 > #999999 or, 153 153 153 > #888888 or, 136 136 136 > #777777 or, 119 119 119 > #666666 or, 102 102 102 > #555555 or, 85 85 85 > #444444 or, 68 58 68 > #333333 or, 51 51 51 > #222222 or, 34 34 34 > #111111 or, 17 17 17 > #000000 or, 0 0 0 > > The final image needs to be saved in a 4 bit (16 color) PNG-8 format with the above exact indexed values. Can someone outline the steps to do this in GC? > > In my case, I am starting with grayscale JPEG images, but I guess starting from color would just take a few extra steps before that. > > Thanks in advance. > Larry >