Image Structure

1.What is the image?

• The pixel is arraied on 2-dimension matrix which is composed of cross grid

• Pixel = Basic unit , picture element

2. The expression method of image

• grayscale image can show 0 ~ 255

• True color image can show 0 ~ 255^3

• Numpy.unit8 could express 1Byte of pixel value ex) ( 255)

• Numpy.ndarray could express 3Byte of pixel value ex) ( 255.255.255) or tuple

• w x h coordinations is generally used in the image.

3. The size analysis of image data

• Gray scale image : ( w ) x ( h ) Bytes
• True color image : ( w ) x ( h ) Bytes

4. The feature of file format

• BMP : It directly save a file without compression

  ​ : The file structure is simple, so it can program the file I/O without extra library help

• JPG : It generally saves color images such as photos

  ​ : Lossly compression

  ​ : It is great compression rate and greatly reduces file size

• GIF : It saves images with 256 colors or less

  ​ : Lossless compression

• PNG : Portable Network Graphics

  ​ : Lossless compression