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

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Anvinder  Singh
Anvinder Singh el 12 de Mzo. de 2016
Comentada: Image Analyst el 13 de Mzo. de 2016
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)

Respuestas (2)

Walter Roberson
Walter Roberson el 12 de Mzo. de 2016
"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 comentarios
Anvinder  Singh
Anvinder Singh el 12 de Mzo. de 2016
Walter, the imagesc doesnt work. The error i get is "Error in imadjust (line 99) validateLowHigh(lowIn,highIn,lowOut,highOut);"
Walter Roberson
Walter Roberson el 12 de Mzo. de 2016
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.

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Image Analyst
Image Analyst el 12 de Mzo. de 2016
Editada: Image Analyst el 13 de Mzo. de 2016
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 comentarios
Anvinder  Singh
Anvinder Singh el 13 de Mzo. de 2016
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
Image Analyst el 13 de Mzo. de 2016
"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.

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