Color Models and Quantization Quiz

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Questions and Answers

How many colors can be represented using 1 bit for each pixel?

256 colors

4 colors

16 colors

2 colors (correct)

Which color model is primarily used for monitors?

YUV

RGB (correct)

HSB

CMYK

With true color representation, how many distinct colors can be represented?

1024 colors

256 colors

2 million colors

16 million colors (correct)

What is the hexadecimal representation for maximum red in the RGB model?

#FF0000 Signup and view all the answers

How many bytes are required to represent true color on a monitor?

3 bytes Signup and view all the answers

Which bit depth allows for 16 shades in an image?

4 bits Signup and view all the answers

What is the primary purpose of indexed color images?

To simplify color management for specific uses Signup and view all the answers

What does the decimal number 255 represent in hexadecimal?

FF Signup and view all the answers

How many bytes does an image that is 1600 pixels by 1200 pixels and requires 3 bytes per pixel occupy?

5,760,000 bytes Signup and view all the answers

What is the approximate size of the image in megabytes if it is 5,760,000 bytes?

5.5 MB Signup and view all the answers

Which of the following statements is true for image files intended for web display?

Quality is more important than file size. Signup and view all the answers

What technique can be used to reduce an image's file size without changing its pixel dimensions?

Compressing the image file Signup and view all the answers

When printing images for flyers or magazines, which factor is considered most important?

Quality of image Signup and view all the answers

What is the maximum number of colors that can be represented in an 8-bit depth image?

256 colors Signup and view all the answers

Which characteristic describes bitmapped images?

Images are resolution dependent and may become jagged when enlarged. Signup and view all the answers

Which of the following is NOT a common bitmap file format?

SVG Signup and view all the answers

What happens to the file size of a bitmapped image when it is enlarged?

It becomes larger. Signup and view all the answers

Why are vector graphic images suitable for logos?

They retain clarity and detail when resized. Signup and view all the answers

What is interpolation in the context of bitmapped images?

Creating new pixels based on existing ones. Signup and view all the answers

Which type of image cannot be easily converted into a vector graphic image?

Photographs in bitmapped form Signup and view all the answers

What is a primary advantage of vector graphics over bitmapped graphics?

Vector graphics retain crisp quality regardless of size change. Signup and view all the answers

Study Notes

Quantizing the Image

1 bit allows for 2 colors (2¹ = 2), typically black and white.
2 bits allow for 4 colors (2² = 4).
4 bits allow for 16 shades.
8 bits allow for 256 shades.
More bits lead to more shades of gray.

Subtractive Model - CMYK

Used in printing.
Ink is applied to paper.
Primary colors are cyan, magenta, and yellow.
Ink subtracts light from white, creating different colors.

Additive Model - RGB

Used on monitors.
Light is emitted from a black background.
Primary colors are red, green, and blue.
Light is added to create different colors.

Representing Colors on a Monitor

True Color:
- Represents 2²⁴ colors (approximately 16 million).
- Requires 3 bytes per pixel (8 bits each for red, green, and blue).
- Can be encoded using decimal numbers (0-255) or hexadecimal codes (#RRGGBB).

Encoding True Colors

Decimal:
- 0 represents no amount of color.
- 255 represents the maximum amount of color.
Hexadecimal:
- #RRGGBB: RR, GG, and BB represent the amount of red, green, and blue respectively.
- 00 in hex corresponds to 0 in decimal.
- FF in hex corresponds to 255 in decimal.
- Examples:
  - #000000 (black)
  - #090807 (dark gray)
  - #0A0F09 (dark green)
  - #FF00FF (magenta)
  - #420063 (purple)

Indexed Color Images

Used when 16 million colors are unnecessary.
An index maps to a specific set of colors used.
Example: Clip art and cartoon images.
Indexed color depth is typically 8 bits, allowing for 256 colors (2⁸).
Each pixel refers to a color from the index, saving space.
Provides a good visual quality despite a limited color palette.

Bitmapped vs Vector Graphic Images

Bitmapped Graphic Image

Made up of pixels arranged in a grid.
Examples: Icons, photographs.
Resolution dependent:
- Images appear larger on lower resolution screens.
- Images become distorted when enlarged.
File size increases when images are enlarged.
Common file formats: BMP, GIF, JPEG, JPG, PNG, PICT, PCX, TIFF.

Vector Graphic Image

Made up of scalable objects defined by mathematical equations.
Objects consist of lines, curves, and shapes.
No distortion when enlarged.
Crisp, clean lines even at large sizes.
Usually have smaller file sizes than bitmapped images.
Ideal for logos and drawings.

Image File Size

Calculated as: Total pixels x Color Bit Depth (in bytes).
Formula: (Length in pixels) x (Width in pixels) x (Color Bit Depth in bytes).
Example:
- 1600 pixels x 1200 pixels x 3 bytes/pixel = 5,760,000 bytes.
- 5,760,000 bytes / 1024 = 5625 kilobytes.
- 5625 kilobytes / 1024 = 5.5 megabytes.

Units of Measure

1 kilobyte (kb) = 1024 bytes (B).
1 megabyte (Mb) = 1024 kilobytes (KB).
1 gigabyte (Gb) = 1024 megabytes (MB).
1 terabyte (TB) = 1024 gigabytes (GB).

Compressing File Size

Option 1: Reducing the physical size of the image, but this affects the displayed size.
- Example: 100 pixel by 100 pixel image (30kb) is smaller than a 200 pixel by 200 pixel image (118kb).
Option 2: Compressing the image file using techniques to reduce file size without sacrificing quality or pixel dimensions.
- Example: A 200 pixel by 200 pixel true color image (200 x 200 x 3 bytes = 120,000 bytes) can be compressed to smaller file size without changing the image's size or resolution.

File Size Considerations

For printing: File size is less important, quality is paramount.
For webpages: File size is critical for fast downloads, quality is also important.

Compression Methods

Lossless compression: Reduces file size without any loss of data.
- Good for preserving image integrity.
- Example: PNG, GIF.
Lossy compression: Reduces file size by discarding some data.
- Good for achieving smaller sizes, but sacrifices some quality.
- Examples: JPEG, JPG.

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Description

Test your knowledge on color quantization and models such as RGB and CMYK. This quiz covers how colors are represented in images and on monitors, including the encoding of true colors. Explore the differences between additive and subtractive color models and their applications in digital imaging and printing.