[vtkusers] About Brightness and Contrast on a Color Image

[Dean Inglis]

VTK source                                        Your Qt project source
      |                                                                   |

vtkSomeClass -> copy over/modify/rename -> vtkMySomeClass
                                                                          |
                                                           recompile and
link to unmodified VTK source/build


On Fri, Apr 19, 2013 at 6:15 AM, Alessandro <notinmyhead at gmail.com> wrote:

> Hi,
>
> so I just add the patched version to my QT project, build, and everything
> will suddenly work?
>
> Ale
>
> Il giorno 18/apr/2013, alle ore 15.13, Dean Inglis ha scritto:
>
> > Hi Ale,
> >
> > I copied the .h and .cxx files for vtkImageMapToWindowLevelColors into a
> new
> > class, applied the patch, and added it to my application which links to
> VTK: no
> > need to alter VTK source or re-build.
> >
> > Dean
> >
> >
> > On Thu, Apr 18, 2013 at 4:43 AM, Alessandro <notinmyhead at gmail.com>
> wrote:
> > 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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>
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