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+--- Thread: Change Amount Channels In Pic (/Thread-Change-Amount-Channels-In-Pic)
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Change Amount Channels In Pic - Winston - 01-18-2021
I was trying to convert a picture to 2 channels, Stereo-chrome, only 2 colors like blue-yellow, red-cyan or green-magenta (similar to color-blindness, inbetween black-and-white and color,) but only had Gray/Alpha. I also tried to use 4 channels for IR-R-G-B, but I don't know how to convert to that from R-G-B-A. All I want to do is make a picture with any amount of channels, any amount of color. Yes, I tried duplicating the channels to the custom channels, but that isn't doing what I want, and won't make yellow-blue or so. Yes, I could mix the channels R with G and have B unchanged, but it still remembers 3 colors, wastes extra space. Yes, I could take the channel number for the picture in HEX and change it, but I tried and it didn't work. And yes, I googled how to do it, but could not find what I want. I'm using GIMP 2.10.8, and Windows 10. Any help would make me happy, or even adding a feature to do that. Do I need to write 'These colors' in HEX when set to 2 channels? Could I set the colors from R-G-B to Y-B? How to hide some invisible channels (like IR)? Is there already a similar format that has only 2-pixels of color? Note: I'm not colorblind, but it is a useful idea if you want to save space but have some color, as it uses less data, or another idea, convert the 2 pixels to audio-spectrum (TFFT stereo audio file), and back.
The attachment is an example of "Blue-And-Yellow" pixels.
Thank you if you don't ban this question.
WARNING: If you do ban this question, you will get 1 star rated. What is wrong with help?
RE: Change Amount Channels In Pic - rich2005 - 01-18-2021
Dear Winston,
Why would we want to ban you? Providing you do not post advertisements / spam / offensive material (or maybe being a general pain-in-the neck) at worst your question is ignored or you might get a great answer, who knows.
Quote:... What is wrong with help?..
Which help are you referring to ? The Gimp help manual is fairly comprehensive but more obscure topics will not be covered. Remember this forum is run by Gimp users for other Gimp users. No Gimp developers here.
Gimp is a RGB bitmap editor, so you are stuck with those channels + transparency. You mentioned an IR channel ? What is that ? To the best of my knowledge Gimp does not have infra-red capabilities.
If you strictly require only two colours then create an indexed image with a 2 entry colour map. Otherwise there are filters to give a 2 colour effect, but you will find in practice with antialiasing you get more that two.
RE: Change Amount Channels In Pic - Winston - 01-18-2021
"create an indexed image with a 2 entry colour map"
How to do that? Is it like 2 grayscale images saved as color maps?
"Gimp does not have infra-red capabilities"
I would like to at least add a channel to my picture so it can store it in the file, even if hidden in most programs.
Similarly, you could in a sound have 1 channel (Mono) or 2 (Stereo), I've managed to make a 3-Channel audio file, but some programs won't play that channel (Played as the center channel). That is basically what I'm trying to do; make a stereo-color, 2-channel image. Is there any format that can store 2-pixel pictures? Or is that outside the box and not invented yet?
If anything, is it possible to make a RAW image with 2 pixels color data?
I just tried saving as an RGBX RAW, with RGBA=BYBY, but it won't open. It saved, but why does it save if it can't read? How do I edit it if I have to insert another file "darktable" or "RawTherapee"? Wouldn't it just be easier if it was already in there?
RE: Change Amount Channels In Pic - rich2005 - 01-18-2021
My problem with your question is one of definitions.
Your two pixel example actually has 1500+ colours as: https://i.imgur.com/5GJSKTS.jpg
Whereas an indexed image with two colours, blue and yellow (three actually, I left black in to define boundaries) as: https://i.imgur.com/BpnZNe8.jpg
Raw Images ? Two types, Photographic RAW, various formats depending on camera make) Import only and a RAW data format which can be exported and opened. To open RAW-data you do need to know the original properties, dimensions, etc (or be good at guessing) as: https://i.imgur.com/Xl1u4cE.jpg
RE: Change Amount Channels In Pic - Winston - 01-18-2021
(01-18-2021, 02:09 PM)rich2005 Wrote: My problem with your question is one of definitions.
Your two pixel example actually has 1500+ colours as: https://i.imgur.com/5GJSKTS.jpg
Whereas an indexed image with two colours, blue and yellow (three actually, I left black in to define boundaries) as: https://i.imgur.com/BpnZNe8.jpg
Raw Images ? Two types, Photographic RAW, various formats depending on camera make) Import only and a RAW data format which can be exported and opened. To open RAW-data you do need to know the original properties, dimensions, etc (or be good at guessing) as: https://i.imgur.com/Xl1u4cE.jpg
Look at Example 1. This has the red-green pixels mixed into yellow. It has shade, unlike Example 2. Example 2 just has one shade of black, blue, and yellow. Is it possible to make a palette with more than one shade of plain blue-and-yellow, perhaps look closer to Example 1?
RE: Change Amount Channels In Pic - rich2005 - 01-18-2021
A two-tone effect ?
You could try something like this:
FG Blue to BG Yellow which gives a FG-to-BG Gradient. Make that active in the Gradient dock.
`Colours -> Map -> Gradient Map gives this:
[attachment=5496]
RE: Change Amount Channels In Pic - denzjos - 01-18-2021
I think you used a GMic-Qt filter to generate the color blindness picture. You can change this color combination with : Colours / Hue-Saturation.
[attachment=5497]
RE: Change Amount Channels In Pic - eepjr24 - 01-18-2021
Trying to learn about the technique being done here. I can follow WHAT is being done, but I don't get the why? What would this type of processing be used for?
- E
RE: Change Amount Channels In Pic - Winston - 01-19-2021
There seems to be a miscommunication.
I'm trying to program a picture file to have 2-channel color, not have one with 3-color only have 2 colors.
For instance, it could be colored #YYBB, #RRCC, or #MMGG, instead of #RRGGBB.
Black-&-White would still be possible, writing as #0000 for black, #8080 for gray, and #FFFF for white. #FF00 would be one color, #00FF would be the inverted color.
Using a different program, I tried looking for "03" hexadecimally in the beginning of picture files representing three colors, and changing it to "02", that didn't work.
Where is this "3" stored in an image file? Is it "2" because it starts from 0; 0=1, 1=2, 2=3? If that is the case, would changing it to 1 (=2) work?
RE: Change Amount Channels In Pic - eepjr24 - 01-19-2021
I don't think channels work like you are thinking. To have a 2 channel image you would need an image format that was designed for only 2 channels. Channels are not mandated to be alterable through file modification, only through translation at time of presentation.
https://en.wikipedia.org/wiki/Channel_(digital_image)
"Channel is a conventional term used to refer to a certain component of an image. In reality, any image format can use any algorithm internally to store images. For instance, GIF images actually refer to the color in each pixel by an index number, which refers to a table where three color components are stored. However, regardless of how a specific format stores the images, discrete color channels can always be determined, as long as a final color image can be rendered."
So modifying the image would not give the result you wanted. You could modify a 3 channel image to only use the colors from 2 channels but again I don't think that is what you are after because it sounds like you want to specify what the channel values are. There may be an image format out there that works in that manner but you are really into a discussion that transcends a particular tool (GIMP in this instance).
- E