05-05-2022, 08:33 AM
(This post was last modified: 05-05-2022, 08:35 AM by rich2005.
Edit Reason: typo
)
As with most graphics, it depends. You can check in Gimp Colors -> Info where there is a color cube analysis (also worth looking at the histogram there)
Second question first:
I am assuming that the pencil drawings are scanned. Scan in color RGB or Grayscale ? It does make a difference.
This various pencils on art paper scanned both ways.
The grayscale scan has 226 colours, the RGB scan 62649 Comparison: https://i.imgur.com/TdOtbbn.jpg
Using Gimp posterize and 7 levels, Grayscale gives 7 colours while the RGB scan does not look that different but there are 112 colors, there are fringes somewhere on the image.
You can get just 7 colours going Image -> Mode -> Greyscale then posterize. If you want to go back to RGB the 7 remain. https://i.imgur.com/nEwux3y.jpg
An easier way ? I do not know one. If you go the grayscale route, then the 7 value posterized palette is equally divided and is #ffffff #d5d5d5 #aaaaaa #808080 #555555 #2b2b2b #000000
Second question first:
Quote:- if I have multiple black and white images all using 7 layers when I posterize the image, will all images automatically have the same 7 values or will they be different slightly for each image?
I am assuming that the pencil drawings are scanned. Scan in color RGB or Grayscale ? It does make a difference.
This various pencils on art paper scanned both ways.
The grayscale scan has 226 colours, the RGB scan 62649 Comparison: https://i.imgur.com/TdOtbbn.jpg
Using Gimp posterize and 7 levels, Grayscale gives 7 colours while the RGB scan does not look that different but there are 112 colors, there are fringes somewhere on the image.
You can get just 7 colours going Image -> Mode -> Greyscale then posterize. If you want to go back to RGB the 7 remain. https://i.imgur.com/nEwux3y.jpg
Quote:- apart from indexing the image, creating a colour palette and then using gradients to print the colour palette, is there an easier way to be able to print out the grey values used?
An easier way ? I do not know one. If you go the grayscale route, then the 7 value posterized palette is equally divided and is #ffffff #d5d5d5 #aaaaaa #808080 #555555 #2b2b2b #000000