如何在MATLAB中转换RGB565和RGB24图像格式？ [英] How can I convert between RGB565 and RGB24 image formats in MATLAB?

问题描述

我从微处理器获取RGB矩阵，输出RGB565格式的图像。我想把它读入MATLAB，将其转换为RGB24格式，然后输出图像。我该怎么做？

解决方案

您首先必须将文本文件中的数据读入MATLAB中的矩阵。由于我不知道您的文本文件的格式，我只能建议您可能需要使用函数和乘法通过比例因子将红色，绿色和蓝色值缩放到0到25​​5的范围，然后使用函数 uint8 。这将为您提供与 img 相同大小的三种颜色分量矩阵：

  imgR = uint8（（255/31）。* bitshift（bitand（img，63488）， -  11））; ％红色成分
 imgG = uint8（（255/63）。* bitshift（bitand（img，2016）， -  5））; ％Green组件
 imgB = uint8（（255/31）。* bitand（img，31））; ％蓝色组件
  

现在您可以使用 cat 将三种颜色的组件放入N-by- M-by-3 RGB图像矩阵，然后使用 imwrite ：

  imgRGB = cat（ 3，imgR，imgG，imgB）; ％沿着第三维连接
 imwrite（imgRGB，'myImage.bmp'）; ％将图像输出到文件
  

示例：

使用随机生成的100 x 100矩阵的uint16值并应用上述转换，结果如下：

  img = randi（[0 65535]，100,100，'uint16'）; 
％执行上述转换以获得imgRGB 
子图（1,2,1）; 
 imshow（img）; 
 title（'Random uint16 image'）; 
 subplot（1,2,2）; 
 imshow（imgRGB）; 
 title（'对应的RGB图像'）; 
  

I am getting an RGB matrix from a microprocessor that outputs an image in RGB565 format. I want to read this into MATLAB, convert it to RGB24 format, and output the image. How do I do this?

解决方案

You first have to read your data from the text file into a matrix in MATLAB. Since I don't know what format your text file is in, I can only suggest that you will probably need to use the function fscanf to read in all of your values (probably of type uint16), then you will likely have to reshape the values into an N-by-M image matrix using the function reshape.

Let's assume you've done all that, and you now have an N-by-M matrix img of unsigned 16-bit integers. First, you can use the function bitand to extract the bits for the red, green, and blue components, whose positions in the 16-bit integer are illustrated here:

Next, you can use the function bitshift and multiplication by a scale factor to scale the red, green, and blue values to a range of 0 to 255, then convert them to an unsigned 8-bit integer using the function uint8. This will give you three color component matrices the same size as img:

imgR = uint8((255/31).*bitshift(bitand(img, 63488), -11));  % Red component
imgG = uint8((255/63).*bitshift(bitand(img, 2016), -5));    % Green component
imgB = uint8((255/31).*bitand(img, 31));                    % Blue component

Now you can use the function cat to put the three color components into an N-by-M-by-3 RGB image matrix, then save the image to an RGB24 bitmap file using the function imwrite:

imgRGB = cat(3, imgR, imgG, imgB);  % Concatenate along the third dimension
imwrite(imgRGB, 'myImage.bmp');     % Output the image to a file

EXAMPLE:

Using a randomly generated 100-by-100 matrix of uint16 values and applying the above conversions, here are the results:

img = randi([0 65535], 100, 100, 'uint16');
% Perform the above conversions to get imgRGB
subplot(1, 2, 1);
imshow(img);
title('Random uint16 image');
subplot(1, 2, 2);
imshow(imgRGB);
title('Corresponding RGB image');

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