一种简单的用于显示HDR的色调映射方法

Posted 2021-01-02 keven-lee

来源于论文 “Fast Bilateral Filtering for the Display of High-Dynamic-Range Images”

 1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 2 % Author: KevenLee
 3 % Contact: [email protected].com
 4 % Date: 20180828
 5 % Version: V1.0.0
 6 % Description: matlab code for simple tonemapping
 7 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 8 
 9 clear
10 clc
11 close all
12 
13 if(~exist(‘memorial.hdr‘))
14     I = double(hdrread(‘office.hdr‘));
15 else
16      I = double(hdrread(‘memorial.hdr‘));
17 end
18 
19 % intensity and r, g, b channel
20 intensity = 0.299 * I(:,:,1) + 0.587 * I(:,:,2) + 0.114 * I(:,:,3);
21 
22 mask = (intensity == 0);
23 intensity = intensity.*(1-mask) + (intensity.*mask+mask.*1);
24 
25 r = I(:,:,1)./intensity;
26 g = I(:,:,2)./intensity;
27 b = I(:,:,3)./intensity;
28 
29 logIntensity = log10(intensity);
30 
31 if(0)
32     logBase=bilateralFilter(logIntensity, [], 0, 1.0, 3, 25);
33 else
34     % you can using guidefilter here, which would be faster.
35     logBase = imguidedfilter(logIntensity,‘NeighborhoodSize‘,[3 3],‘DegreeOfSmoothing‘,0.1);
36 end
37 % details in log10 domain
38 logDetail = logIntensity - logBase;
39 
40 % compression factor. log10(5) for default. You can modify it. visually, larger
41 % darker, smaller lighter
42 compressionfactor = log10(5)/(max(logBase(:)) - min(logBase(:)));
43 log_absolute_scale= max(logBase(:))*compressionfactor;
44 
45 logOutIntensity = logBase.*compressionfactor + logDetail - log_absolute_scale;
46 
47 % adjust every channel.
48 routput = r.*10.^(logOutIntensity);
49 goutput = g.*10.^(logOutIntensity);
50 boutput = b.*10.^(logOutIntensity);
51 
52 % output image
53 OI = cat(3, routput,goutput,boutput);
54 
55 % you can add some operators here. etc. color balance
56 output = uint8(OI.*255);
57 
58 % saving as 8-bits jpg image
59 imwrite(output, ‘tonemapping.jpg‘);
60 imwrite(I, ‘hdr.jpg‘);
61 
62 figure(‘Name‘, ‘hdr image‘),imshow(uint8(I)),title(‘hdr image‘)
63 figure(‘Name‘, ‘toneMapping‘),imshow(output),title(‘toneMapping‘)

 

具体结果如下，左边是线性压缩到8bit的图像，右图是tonemap后的图像。

 

参考

 https://www.cnblogs.com/Imageshop/p/3428809.html