# Week #5 \~ Optional Section
## :rainbow: RGB | CMYK channels :rainbow:
There are two different color modes that represent Primarily (GRB) and secondary colors (CMYK).
RGB is based on the way the human eye perceives the color of the light! The absence of color in RGB mode makes the **black** color and the maximum amount of combination of all RGB makes the **white** color, while the combination of **CMYK** inks creates **black** and the absence creates **white.**
In RGB mode, Black is the absence of color and white shows where the color is. In CMYK this rule is the opposite! In RGB mode, the Black brush **removes** components of a channel and the White Brush brings it back. In CMYK this rule is the opposite!
* when RGB colors mix together in pair, they create CMYK color
* Secondary colors (CMYK) are complementary colors to the remaining primarily color (RGB)!
**RGB/CMYK Mode in Ps**
In Photoshop you can work in different color modes. Photoshop default color mode is RGB 8 Bits. RGB is the right mode for any screen-based work such as web or digital devices. CMYK is the right mode for printing.
If you decide to change the mode you can change it from the **Image** menu!
Color channels are created automatically when you open a new image. The image’s color mode determines the number of color channels created. If you choose RGB images use **three** channels to reproduce colors on the screen *(Red, Green, Blue)*. If if you choose CMYK images use **four** channels to reproduce colors on the screen *(Cyan, Magenta, Yellow, Black).*
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**Some fun experiments with Color Channels**
to work with this technique you need to pay attention to some important points before you start working with *color channels:*
* Monotone images are better for this technique.
* All layers should be flattened.
* Have a solid white background is better.
* The Composite color channel and all color channels should be visible in order to save the final work.
* If you want to copy from an image and paste it to another image, the color mode should be the same and all layers should be fattened.
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In this video. I will show you some techniques using Invert, Selection, Fill/Gradient, Transform, Brush and Smudge tool, Adjustment tools**,** and Copy and Paste from another image!
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