I want to change the gray scale from [0 1] to [0 500]

5 次查看（过去 30 天）

显示更早的评论

Anvinder Singh 2016-3-12

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/272997-i-want-to-change-the-gray-scale-from-0-1-to-0-500

评论： Image Analyst 2016-3-13

在 MATLAB Online 中打开

I want to change the gray scale from [0 1] to [0 500] and have used the following functions

b= imadjust(a,[0; 1],[0; 500])

and

%j = imadjust(a,stretchlim(a),[0 500]);

but they don't seem to work. There are errors when i plot them.

CODE:

 a = ones(256, 256, 3);
 a(10:110,40:100,:)=0;
 a(120:200,120:200,:)=0;
 %colormap('gray');
 image(a)
 figure();
 b= imadjust(a,[0; 1],[0; 500])
 %j = imadjust(a,stretchlim(a),[0 500]);
 image(b)

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

回答（2 个）

Walter Roberson 2016-3-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/272997-i-want-to-change-the-gray-scale-from-0-1-to-0-500#answer_213329

"By default, the CDataMapping property for the image is set to 'direct' so image interprets values in C as indices into the colormap. For example, the bottom right pixel corresponding to the last element in C, 22, uses the 22nd color of the colormap."

Do you have 500 colors or more in your colormap?

4 个评论
显示 2更早的评论隐藏 2更早的评论

Anvinder Singh 2016-3-12

Walter, the imagesc doesnt work. The error i get is "Error in imadjust (line 99) validateLowHigh(lowIn,highIn,lowOut,highOut);"

Walter Roberson 2016-3-12

Then that was not errors when you plot them, that was errors when you did the adjustment. And you did not post the complete error message.

请先登录，再进行评论。

Image Analyst 2016-3-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/272997-i-want-to-change-the-gray-scale-from-0-1-to-0-500#answer_213348

编辑：Image Analyst 2016-3-13

在 MATLAB Online 中打开

How about using mat2gray():

b = 500 * mat2gray(a);

It scales min to max, whereas imadjust() scales based on percentage of counts in the histogram tails. Just depends on what you want to do.

16 个评论
显示 14更早的评论隐藏 14更早的评论

Image Analyst 2016-3-13

在 MATLAB Online 中打开

Come on. It does not. Here's a full blown demo:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
% Make all white.
grayImage = ones(256, 256);
% Make some rectangles black.
grayImage(10:110,40:100) = 0;
grayImage(120:200,120:200) = 0;
subplot(3, 1, 1);
imshow(grayImage);
axis on;
colormap(gray(500));
colorbar;
title('Original Image', 'FontSize', fontSize);
% Scale the image intensity to between 0 and 500
scaledImage = 500*mat2gray(grayImage);
subplot(3, 1, 2);
imshow(scaledImage, []);
axis on;
colormap(gray(500));
colorbar;
title('Scaled Image', 'FontSize', fontSize);
% Make noisy image where lambda is the value of the image at that location
noisyImage = poissrnd(scaledImage);
subplot(3, 1, 3);
imshow(noisyImage, []);
title('Noisy Image', 'FontSize', fontSize);
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
% Get rid of tool bar and pulldown menus that are along top of figure.
set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off')

Anvinder Singh 2016-3-13

Oh, Thanks Image analyst. Just forgot it will have no poisson noise for '0' value. It seems to be good. One last thing, if i need the background to be white i am trying to change "grayimage = ones(256, 256);" and grayscale value but it doesnt seem to show up ?

Image Analyst 2016-3-13

"White" is going to be the brightest value in your image, which is 500, not 1. Assign areas you want to be white to 500, not 1.

请先登录，再进行评论。

请先登录，再回答此问题。

类别

MATLAB Graphics Formatting and Annotation Colormaps Red

在 Help Center 和 File Exchange 中查找有关 Red 的更多信息

产品

Image Processing Toolbox

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by