EE4206/EE5806 Digital Image Processing

EE4206/EE5806 Digital Image Processing

quoted from Digital Image Processing : An algorithmic Introduction Using Java by Burger and Burge (2008) page : 57-58
Automatic Contrast Adjustment


1. Automatic constrast adjustment (auto-contrast) is a point operation whose task is to modify the pixels such that the available range of values is fully covered.

2. This is done by mapping the current darkest and brightest pixels to the lowest and highest available intensity values respectively, and linearly distributing the intermediate values.

3. Original pixel values a in the range [a-low, a-high] are mapped linearly to the target range[a-min, a-max].

4. Let us assume that a-low and a-high are the lowest and highest pixel values found in the current image, whose full intensity range is [a-min, a-max].

5. To stretch the image to the full intensity range, we first map the smallest pixel value a-low to zero, subsequently increase the contrast by the factor (a-max - a-min)/ (a-high - a-low), and finally shift to the target range by adding a-min.

我知道自己存在，而且在探究這個存在的「我 」到底是什麼。因此，嚴格說來，有關我對自己存在所有的知識，絕對不能依靠我不知道其存在的那些事物，由此可知，這種知識也不能依靠我想像中虛構的任何事物。

其實，「 在想像中虛構 」或 「 我構成一個影像」這類說法，就足以證明我的錯誤。因為如果我想像自己是一種東西，則我非得構成一個影像不可，而所謂想像，只是思維有形物體的形狀 ( figure）或 影像（ image）罷了。

不過我已確實知道我是存在的，而且一般說來，這些影像就是與物體本性有關的事物，也許只是一些夢境或幻想而已。

因此，我實在沒理由說：「 為了較清晰地知道自己是什麼，所以我應該刺激自己的想像。 」