Theory

The reason why the appearance of your picture on each screen is exactly equal is because the colors in your photo are taken by your digital camera, but that they are made in the output device you work with. For example, the screen of your computer or printer.

So before I start with this subject, I’d first try to explain just how the colors on your screen are to be created and what modes that are available to display them.

In Photoshop, we have three different modes to display our photos, RGB (1), CMYK (2) and Lab (3).

This aside, the mode in which your digital camera takes your picture is RGB.

So you need to change this for one reason or another, you do this in Photoshop.

We continue.

All these modes consist of gray values. The composition of these gray levels, gives the color in our picture on the screen.

An example.

The RGB mode, which is the default mode of our digital camera, consists of four channels. Three of them are taken by our digital cameras, Red, Green and Blue and a fourth RGB is compiled by Photoshop, or rather, your screen.

To bring evidence to all this, we first open the “Channels” panel.

If you only look at the blue channel (1), you see that the colors in this channel only consist of dark gray. This is called “Shadows” (shadows).

The green channel consists of medium gray (2), which is called the “Midrange” (Midtones).

And the red channel only consists of light gray (3), which is called the ‘Highlights’ (Highlights).

Looking at the composition of these three channels(4), we see, you guessed it, color.

Knowing this, the conclusion is not doubtful. Set the grayscale for the photo correctly, and you have a perfect view of your photo.

Bit depth / Color Depth

The Bit depth, also known as color depth, is the unit of measurement for the amount of colors a pixel can display. For example, a pixel in an 8-bit images has the ability to display 256 nuances and this is for each channel.  Where’d you get 256 shades?
A black / white photograph or to put it in Photoshop words a bitmap, has a bit depth of 1, the pixel is either black or white. One of the two.
In short, a picture with a bit depth of 1 is 1 X 2 = 2. So 2 gray levels, white or black.

And a photo with a bit depth of 8 is 2 X 2 X 2 X 2 X 2 X 2 X 2 X 2 = 256.

So 256 gray levels per channel.

Each gray value is displayed with a number. So Black has the value 0, and white has the value 255.

So you see that the pixel in the image below where I move on with the eyedropper (1), has a value of 84 in the red channel, 69 in the green channel and 62 in the blue channel (2). This is so obvious when you show only the red channel (3).

When we know that each channel has 256 different color values, it is easy to calculate how many colors our picture has. 256 X 256 X 256 = 16,777,216 colors.

If you like three channels in an RGB image, then you will need a photo with a bit depth of 24.

In CMYK images, we have four channels, so a bit depth of 32.

This was all just theory, the only thing you should remember is that by adjusting the grayscale, you can change the colors in a photograph. And the lower the gray value, the darker the color becomes.

RGB, CMYK or Lab

Simple, always RGB.

Why Because, your photos from your digital camera are taken in RGB, two, because it is easier to work with three instead of four channels and three because you can work correctly with RGB than CMYK.

So unless you are sending your photos to a professional printer and they request for it, do not change the setting from RGB to CMYK.

But otherwise, keep it in RGB.

You can use Lab to sharpen or blur your photos and adjust the contrast or brightness by touching the colors in your picture.

But unless you are a professional, it’s best and easiest to work in RGB.

To change mode of your photo, click the “Image” in the menu bar, choose “Mode” in the drop-down menu, and make a choice.

You can change the mode of your photo at any time. This does nothing to the display of your photo.

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