[vtkusers] About Brightness and Contrast on a Color Image

[Alessandro]

Hi,

thanks for the answer! So, if I'm not wrong, all I need to do is re-build the library applying the patch in advance?

Do you think to submit this patch to vtk repository to include it in further vtk versions?

Thank,
Ale

Il giorno 17/apr/2013, alle ore 15.01, Dean Inglis ha scritto:

> Hi Alessandro,
> 
> for unsigned char 3 component images, I wrote a customized version of vtkImageMapToWindowLevelColors to work on multi-component images.  In the unmodified
> (vtk) version of this class, only the first component of multi-component images is modified, as described in the class documentation:
> 
> "The vtkImageMapToWindowLevelColors filter will take an input image of any valid scalar type, and map the first component of the image through a lookup table. This resulting color will be modulated with value obtained by a window / level operation. The result is an image of type VTK_UNSIGNED_CHAR. If the lookup table is not set, or is set to NULL, then the input data will be passed through if it is already of type UNSIGNED_CHAR."
> 
> here are the mods to lines 366 to 401 of vtkImageMapToWindowLevelColors.cxx in VTK 5.10
> 
> 364       else
> 365         {
> 366         for (idxX = 0; idxX < extX; idxX++)
> 367           {
> 368           for(int j = 0; j < numberOfComponents; ++j )
> 369             {
> 370             if( j == (numberOfComponents - 1 ) &&
> 371                 (outputFormat == VTK_LUMINANCE_ALPHA ||
> 372                  outputFormat == VTK_RGBA) )
> 373               {
> 374               *(optr) = 255;
> 375               }
> 376             else
> 377             {
> 378             if (*iptr <= lower)
> 379               {
> 380               result_val = lower_val;
> 381               }
> 382             else if (*iptr >= upper)
> 383               {
> 384               result_val = upper_val;
> 385               }
> 386             else
> 387               {
> 388               result_val = static_cast<unsigned char>((*iptr + shift)*scale);
> 389               }
> 390             *optr = result_val;
> 391             }
> 392             iptr++;
> 393             optr++;
> 394             }
> 395           }
> 396         }
> 
> 
> regards,
> Dean
> 
> 
> 
> On Tue, Apr 16, 2013 at 5:02 PM, Alessandro <notinmyhead at gmail.com> wrote:
> Hi,
> 
> I'm trying to apply Brightness and Contrast to a blended image, created from a Grey Image and a Color one. I set brightness and contrast via vtkImageViewer2 SetColorWindow and SetColorLevel methods but it doesn't work on the blended one: as soon as I set one of them, the image becomes a Grey one.
> 
> Any suggestion?
> 
> Thanks,
> Ale
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