1 Project Files

2 Project Description

Decolorization - the process to transform a color image to a grayscale one - is a basic tool in digital printing, stylized black-and-white photography, and in many single channel

image processing applications

Model

The decolorization function is defined as g = f(c), which is a mapping from color image c to gray image g.

The mapping function is further expressed as

where {m} is the set of monomial basis and {w} is the corresponding coefficients.

With the weak color order assumption, the energy function w.r.t parameter {w} can be finally written as

Algorithm

The overall algorithm is like this

3 Implementation

The implementation is using MATLAB with the skeleton code provided. The main acceleration skill is to use 2D filter [1,-1] and [1;-1] to get the difference between neighbors.

4 Experiments

Test Images

Here we got 10 test images, with different contents. They are

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\1.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\2.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\3.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\4.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\5.png$

Image 1 Image 2 Image 3 Image 4 Image 5

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\6.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\7.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\8.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\9.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\10.png$

Image 6 Image 7 Image 8 Image 9 Image 10

Parameters

In this program, there is one only one parameter we need to set. That is the variation of Gaussian functions, .

Here I use the

Experiment Results

Then we get 10 output image, listed below. Their original image are shown next to each image.

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\1.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\1.png$

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\2.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\2.png$

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\3.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\3.png$

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\4.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\4.png$

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\5.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\5.png$

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\6.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\6.png$

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\7.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\7.png$

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\8.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\8.png$

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\9.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\9.png$

$Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\outImage\10.png$ $Description: Description: Description: C:\Course\Image Processing and CV\Projects\3\cpcolor2gray code\test images\10.png$

Numeric Evaluation

Using the function ccpr(), we get the following ccpr value:

Text Box: MY 67.13 65.7 64.74 63.25 62.34 60.95 59.65 58.74 57.67 56.82 55.81
YUV 58.24 56.38 55.26 53.84 52.87 51.71 50.56 49.7 48.52 47.98 47.06
CIE LAB 56.32 54.73 53.74 52.35 51.49 50.25 48.86 47.9 46.76 46.24 45.53

We can set that the CCPR significantly improved the contrast of decolorized picture.

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