32 bits effect on tif images

hi;

why when I convert my gray images to 32 bits by using uint32 instruction they get 'sombre',what can I do?

my images '*.tif*' are gray with points dark 'microscopic images ',when I show them under Matlab

they appear so sombre ,this is after I converted them to Unit32.

[Walter Roberson]

Could you post an example?

[Image Analyst]

What does sombre mean?

Answer 1

[Anand]

If you're problem is that you are converting to uint32 with a direct cast like uint32(im) and then calling imshow for display, the solution is simple. Use the display range of imshow.

im = imread('cameraman.tif');
figure,imshow(uint32(im));title('sombre image');
figure,imshow(uint32(im),[]);title('bright image');

[Anand]

You need to provide more details. What 'treatment'? Could you post some code for that? How are you converting to UINT32.

Try rescaling the image to the full dynamic range of the data type.

im = imread('cameraman.tif');
imd = double(im);
imnorm = (imd-min(imd(:)))./(max(imd(:))-min(imd(:)));
range = getrangefromclass(uint32(1))
imu = uint32( imnorm*(range(2)-range(1)) + range(1) );

[Walter Roberson]

Please show the code you used.

[Ivo Marten Glück]

I have a very similar problem. I'm using the following code to generate a 32-bit TIFF image. I can read the resulting image into Matlab using imread, however it is not depicted correctly after opening in ImageJ and cannot be read by Adobe Illustrator. Any idea what is wrong?

heigth  = round((max(y_coords)-min(y_coords))/pixel_size_image);
width   = round((max(x_coords)-min(x_coords))/pixel_size_image);

im = hist3([y_coords,x_coords],[heigth width]);
imG = imgaussfilt(im, pixel_size_image/5);
figure; imshow(imG);
range = getrangefromclass(uint32(1));
I32 = uint32( imG*(range(2)-range(1)) + range(1) );


t = Tiff(strcat(SR_image_name, '.tiff'),'w');                               
tagstruct.ImageLength     = size(I32,1);
tagstruct.ImageWidth      = size(I32,2);
tagstruct.Photometric     = Tiff.Photometric.MinIsBlack;
tagstruct.BitsPerSample   = 32;
tagstruct.SamplesPerPixel = 1;
tagstruct.RowsPerStrip    = 16;
tagstruct.PlanarConfiguration = Tiff.PlanarConfiguration.Chunky;
tagstruct.Software        = 'MATLAB';
t.setTag(tagstruct)

t.write(I32);
t.close()

Many thanks!