MantisBT - ITK |
| View Issue Details |
|
| ID | Project | Category | View Status | Date Submitted | Last Update |
| 0010917 | ITK | | public | 2010-06-30 08:16 | 2010-11-16 12:06 |
|
| Reporter | aurelien | |
| Assigned To | kentwilliams | |
| Priority | normal | Severity | major | Reproducibility | always |
| Status | closed | Resolution | fixed | |
| Platform | | OS | | OS Version | |
| Product Version | ITK-3-18 | |
| Target Version | | Fixed in Version | ITK-4-A2 | |
| Resolution Date | 2010-11-16 |
| Sprint | |
| Sprint Status | completed |
|
| Summary | 0010917: Cannot read a RGBA png file into an itk::Image<unsigned char, 2> properly |
| Description | I tried to read a 4 channels (RGBA) png image file into an
itk:Image<unsigned char, 2> and the output image makes no sense. It
appears that it works fine with RGB png images. In fact, I located the
issue in ConvertPixelBuffer::ConvertRGBAToGray() that computes the
grayscale pixel value by applying the following formula:
((2125.0 * static_cast<double>RedPixelValue +
7154.0 * static_cast<double>GreenPixelValue +
0721.0 * static_cast<double>BluePixelValue)/1000.0) //OK
* static_cast<double>AlphaPixelValue
//Here is the issue
In a RGBA png image, the range of AlphaPixelValue is [0,255]. The
resulting grayscale value is no longer reasonably allowed to be casted
into an unsigned char. That's why the reader output doesn't make any
sense. I isolated this behavior in the attachment. |
| Steps To Reproduce | |
| Additional Information | a fix is pushed to gerrit |
| Tags | No tags attached. |
| Relationships | |
| Attached Files |  PngReadWriteBug.tar.gz (43,437) 2010-06-30 08:16
https://public.kitware.com/Bug/file/3217/PngReadWriteBug.tar.gz |
|
| Issue History |
| Date Modified | Username | Field | Change |
| 2010-06-30 08:16 | aurelien | New Issue | |
| 2010-06-30 08:16 | aurelien | File Added: PngReadWriteBug.tar.gz | |
| 2010-11-02 14:14 | Hans Johnson | Status | new => assigned |
| 2010-11-02 14:14 | Hans Johnson | Assigned To | => Gabe Hart |
| 2010-11-02 14:15 | Hans Johnson | Assigned To | Gabe Hart => kentwilliams |
| 2010-11-04 12:43 | kentwilliams | Sprint Status | => active |
| 2010-11-04 12:43 | kentwilliams | Additional Information Updated | |
| 2010-11-16 12:06 | kentwilliams | Resolution Date | => 2010-11-16 |
| 2010-11-16 12:06 | kentwilliams | Sprint Status | active => completed |
| 2010-11-16 12:06 | kentwilliams | Status | assigned => closed |
| 2010-11-16 12:06 | kentwilliams | Resolution | open => fixed |
| 2010-11-16 12:06 | kentwilliams | Fixed in Version | => ITK-4-A2 |