Courses IB Computer Science (Standard) Data Color Images

Color Images

LED Computer Screens

This image shows a close-up of a computer screen’s pixels, each made of red, green, and blue subpixels. These subpixels glow at different brightness levels to create millions of colors—your eyes blend them into smooth images.

Screens use the RGB color model, where mixing red, green, and blue light in various intensities forms all visible colors.

In LCD screens, a white LED backlight shines through color filters controlled by liquid crystals.
In OLED screens, each subpixel emits its own light, allowing true blacks and better contrast.
Together, these tiny RGB elements form every picture you see on a display.

Image source: Wikipedia

RGB Color Images

The RGB color model uses the three primary additive colors: red, green, and blue, with each color channel ranging from 0 to 255. In this system, a total of 256 intensities are available for each channel, resulting in over 16.7 million possible colors (256^3).

Red : 0 to 255 (8 bits / 1 byte)

Green: 0 to 255 (8 bits / 1 byte)

Blue: 0 to 255 (8 bits / 1 byte)

Each color requires 8 bits and therefore the color depth of an RGB images is 24 bits / 3 Bytes.

RGB color demonstration

Red: 128

Green: 128

Blue: 128

How many bits are typically used to represent the color intensity for each channel in an RGB image?

{"answers": {"A": "8 bits", "B": "16 bits", "C": "24 bits", "D": "12 bits"}, "question_text": "How many bits are typically used to represent the color intensity for each channel in an RGB image?", "correct_answer": "A"}

Which primary color in RGB is associated with the value (255, 0, 0)?

{"answers": {"A": "Green", "B": "Cyan", "C": "Red", "D": "Blue"}, "question_text": "Which primary color in RGB is associated with the value (255, 0, 0)?", "correct_answer": "C"}

What is the result of adding pure red (255, 0, 0) and pure green (0, 255, 0) in RGB color model?

{"answers": {"A": "Black", "B": "Magenta", "C": "Cyan", "D": "Yellow"}, "question_text": "What is the result of adding pure red (255, 0, 0) and pure green (0, 255, 0) in RGB color model?", "correct_answer": "D"}

{"keyword": "color depth", "definition": "The number of bits used to represent the color of a single pixel."}

Bit Depth

Bit depth, also known as color depth, is the amount of color information stored in each pixel of an image. It determines how finely an image can represent color variations and is measured in bits.

The higher the bit depth, the greater the number of colors that can be represented, resulting in richer, more detailed images.

The bit depth defines how many bits are used to store the information for each of these color channels.

The most common bit depth is 8 bits per channel for RGB, resulting in a bit depth of 24 bits per pixel.

The term 'bit depth' refers to the number of [[bits]] used to represent the color of a single pixel in an image.

{"cloze_text": "The term 'bit depth' refers to the number of [[bits]] used to represent the color of a single pixel in an image."}

Image Bit Depth Examples

Higher bit depths allow for a greater range of [[colors]] in an image, resulting in more accurate color representation.

{"cloze_text": "Higher bit depths allow for a greater range of [[colors]] in an image, resulting in more accurate color representation."}

Review: Fill in the Blanks

The , also known as the , is a widely used color system in computer graphics and digital imaging. It is based on the concept of combining red, green, and blue light together to create a broad spectrum of colors. In this model, each color is represented by a combination of the intensity levels of the three primary colors.

To specify colors in the RGB color model, different methods can be used, and one popular approach is through the use of s. A , short for hexadecimal code, is a six-digit alphanumeric value that represents a specific color.

, another important aspect of the RGB color model, refers to the number of bits used to represent each primary color. The higher the color depth, the more distinct colors can be created. For example, a color depth of 24 bits allows for approximately 16.8 million different colors to be displayed.

Click the keywords below to fill in the blanks:

Additive Color Mixing Hex Code Rgb Color Model Color Depth Hex Color Code

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