GIMP Chat :: Please Help, I Cannot get the correct value using the color picker.

ShangZhou wrote:

GIMP Version: 2.10.22
Operating System: Windows
OS Version: win7
GIMP Experience: Basic Level

I have two color areas (0, 0, 0) and (128, 128, 128).Then I set the pick radius of the color picker to 30 pixels. But I keep getting (91,91,91) instead of (64,64,64).
I think it may be related to the composition space, because I have to manually set the layer composition space to sensory every time. Otherwise, it will be linear light.（Sorry for my english, i used google translate．I don’t know if it expresses clearly，）　．

Well, no... You are considering light as a linear phenomenon, while your actual perception is logarithmic.

Try this: Create 3 images side by side on your screen. Fill the leftmost wih 91, the right most with 64, and fill the middle one with a small checker board (or thin stripes of equal width) of black (0) and 50% gray (128). No go tp the other side of the room and look at your screen. On xhich side is the image that looks like the center one?

So the average of 0 and 128 (in other words, the overall color of an image that is half black and half mid-gray) is 91 and not 64 a,d that what the color picker is telling you.

Author:	ShangZhou [ Thu Jan 07, 2021 8:49 am ]
Post subject:	Please Help, I Cannot get the correct value using the color picker.
GIMP Version: 2.10.22 Operating System: Windows OS Version: win7 GIMP Experience: Basic Level I have two color areas (0, 0, 0) and (128, 128, 128).Then I set the pick radius of the color picker to 30 pixels. But I keep getting (91,91,91) instead of (64,64,64). I think it may be related to the composition space, because I have to manually set the layer composition space to sensory every time. Otherwise, it will be linear light.（Sorry for my english, i used google translate．I don’t know if it expresses clearly，）　．

Author:	ofnuts [ Thu Jan 07, 2021 5:40 pm ]
Post subject:	Re: Please Help, I Cannot get the correct value using the color picker
ShangZhou wrote: GIMP Version: 2.10.22 Operating System: Windows OS Version: win7 GIMP Experience: Basic Level I have two color areas (0, 0, 0) and (128, 128, 128).Then I set the pick radius of the color picker to 30 pixels. But I keep getting (91,91,91) instead of (64,64,64). I think it may be related to the composition space, because I have to manually set the layer composition space to sensory every time. Otherwise, it will be linear light.（Sorry for my english, i used google translate．I don’t know if it expresses clearly，）　． Well, no... You are considering light as a linear phenomenon, while your actual perception is logarithmic. Try this: Create 3 images side by side on your screen. Fill the leftmost wih 91, the right most with 64, and fill the middle one with a small checker board (or thin stripes of equal width) of black (0) and 50% gray (128). No go tp the other side of the room and look at your screen. On xhich side is the image that looks like the center one? So the average of 0 and 128 (in other words, the overall color of an image that is half black and half mid-gray) is 91 and not 64 a,d that what the color picker is telling you.

Author:	ShangZhou [ Thu Jan 07, 2021 8:02 pm ]
Post subject:	Re: Please Help, I Cannot get the correct value using the color picker
ofnuts wrote: ShangZhou wrote: GIMP Version: 2.10.22 Operating System: Windows OS Version: win7 GIMP Experience: Basic Level I have two color areas (0, 0, 0) and (128, 128, 128).Then I set the pick radius of the color picker to 30 pixels. But I keep getting (91,91,91) instead of (64,64,64). I think it may be related to the composition space, because I have to manually set the layer composition space to sensory every time. Otherwise, it will be linear light.（Sorry for my english, i used google translate．I don’t know if it expresses clearly，）　． Well, no... You are considering light as a linear phenomenon, while your actual perception is logarithmic. Try this: Create 3 images side by side on your screen. Fill the leftmost wih 91, the right most with 64, and fill the middle one with a small checker board (or thin stripes of equal width) of black (0) and 50% gray (128). No go tp the other side of the room and look at your screen. On xhich side is the image that looks like the center one? So the average of 0 and 128 (in other words, the overall color of an image that is half black and half mid-gray) is 91 and not 64 a,d that what the color picker is telling you. xd，Well,Thank you， I learned some new knowledge. . But is there a way to make it give me the result of (64, 64, 64). I use GIMP to do some digital painting. This is very important to my workflow.

Author:	ShangZhou [ Thu Jan 07, 2021 10:10 pm ]
Post subject:	Re: Please Help, I Cannot get the correct value using the color picker
lylejk wrote: Just doubleclick on your foreground color and type in the values. Lol , my fault ,or you just kidding. I mean let the color picker give me the linear result. But I have found an alternative method for my workflow, so if there is no way, it's okay, though,just it's not so convenient.....

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