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#1 Posted : Thursday, October 22, 2009 7:40:50 PM(UTC)
omarelgazzar11

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I'm trying to apply modality, voi, presentation LUT using leadtools v.13 using Delphi.
I'm using the LevelLut[i] property to set the color of each gray level in the bitmap.
The problem is that the LUT data are 16 bits and I want to convert this 16 bits value (0-635536) to TColor (RGB).
I tried to scale the 16-bits value to 8-bits (gray = 0-256) and using
leadimage1.LevelLut[i]:=RGB(gray,gray,gray);
but the output result is not correct.
Can you help me in this regard?
Thanks,


 

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#2 Posted : Sunday, October 25, 2009 4:33:20 AM(UTC)

Basel  
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It appears you're using the LEADTOOLS VCL components, is this correct?
In any case, the LevelLut entries are regular 24-bit color values. The index of the array property corresponds to the gray level.

This means if you have a 16-bit grayscale image, the entries will be from LevelLut[0] to LevelLut[65535]. You can assign any color to each level as desired.

For example, to display the pure black pixels as red, you assign RGB(255, 0, 0) to LevelLut[0].
As another example, to display pure black pixels as green on the screen, you assign RGB(0, 255, 0) to LevelLut[65535].

If you want to display grayscales as similar-looking gray, you assign the following:
LevelLut[n] := RGB(x, x, x), where n ranges from 0 to 65535 and x = n/256.
 
#3 Posted : Monday, October 26, 2009 3:33:43 AM(UTC)
omarelgazzar11

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Dear Mr.Basel,

Thank you for your hint...

What if the image is signed (e.g 12 bits in 16 bits image that has values from -2048 to +2047)?. In this case, I cannot pass a -ve index corresponding to -ve grayscale level to the function LevelLut[n] when n<0.
How can I solve this problem?.

thanks,
 
#4 Posted : Monday, October 26, 2009 5:44:23 AM(UTC)

Basel  
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You can check the IsSigned property and if it's true, use the ConvertSignedToUnsigned method to convert the image values to the non-negative range.

 
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