Processing 補充教材 --- image

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Digital photographs are fundamentally different from analog photographs captured on film.
Like computer screens, digital photos are rectangular grids of color.
The dimensions of digital images are measured in units of pixels.
If an image is 320 pixels wide and 240 pixels high, it has 76,800 total pixels.
If an image is 1280 pixels wide and 1024 pixels wide, the total number of pixels is an impressive 1,310,720 (1.3 megapixels).
Every digital image has a color depth.
The color depth refers to the number of bits (p. 669) used to store each pixel.
If the color depth of an image is 1, each pixel can be one of two values, for example, black or white.
If the color depth is 4, each pixel can be one of 16 values.
If the color depth of an image is 8, each pixel can be one of 256 values.
Looking at the same image displayed with different color depths reveals how this affects the image’s appearance:


數位影像基本上與類比影像是不同的
數位影像好比電腦螢幕 它是一個由一個充滿顏色的矩形所組成
數位影像的大小是由像素點來衡量
假如一張影像的寬有320個像素點 高有240個像素點 那麼這張影像共有76,800個像素點
假如一張影像的寬有1280個像素點 高有1024個像素點 那麼這張影像像素點的個數相當驚人 共有1,310,720點(約1.3 mega )
而每一個數位影像有一個色彩深度
其中色彩深度指的是用來儲存每一個像素點所需的bit數
假如一張影像的色彩深度為1 那麼每個像素點有兩個數值可以選 如 黑色或白色
假如色彩深度為4 那麼每個像素點的顏色就有16種選擇
同樣的 假如色彩深度為8 那麼每個像素點有256種的顏色可以選
由上可知 同一張影像因不同的色彩深度會有不同的外觀展現