digital image processing projects 数字图像处理 冈萨雷斯 第三(2)

【2】power-law transformation

I=imread('Fig3.08(a).jpg'); subplot(221); imshow(I); title('original');

J=double(I);

I1=im2uint8(mat2gray(J.^0.6)); subplot(222); imshow(I1);

title('power-law:\\gamma=0.6');

I2=im2uint8(mat2gray(J.^0.4)); subplot(223); imshow(I2);

title('power-law:\\gamma=0.4');

I3=im2uint8(mat2gray(J.^0.3)); subplot(224); imshow(I3);

title('power-law:\\gamma=0.3');

Discussion of results

originallog transformation

Figure 3 results of log transformation

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originalpower-law:?=0.6power-law:?=0.4power-law:?=0.3Figure 4 results of power-law transformation

Analysis

Log transformation can diminish dynamic range of the image. Power-law transformation can change the contrast of the image.

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Histogram Equalization

Exp. 6，PROJECT 03-02 [Multiple Uses]

Objective

To manipulate a technique of image enhancement by histogramequalization.

Requirements

(a) Write a computer program for computing the histogram of animage. (b) Implement the histogram equalization technique discussed inSection 3.3.1. (c) Download Fig. 3.8(a) and perform histogram equalization on it.

Figure 5 3.8(a)

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Technical discussion

【1】J = histeq(I, n)

transforms the intensity image I, returning in J an intensity image with n discrete gray levels. 【2】imhist(I)

displays a histogram for the image I above a grayscale colorbar.

Program listings

I=imread('Fig3.08(a).jpg'); subplot(221); imshow(I);

subplot(222); imhist(I);

I1=histeq(I,256); subplot(223) imshow(I1);

subplot(224); imhist(I1);

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Discussion of results

15000100005000001002001500010000500000100200

Figure 6 the results of project 03-02

Analysis

We can see more details in the dark part.

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