There is a problem when NEF files are read directly or used as input for a batch conversion. Highlights have a magenta cast instead of being white. This is due to a preconditioning of the raw channels, so that not all channels clip at the same value. More information about this pre-conditioning can be found on this forum thread:
Using automatic white balance or the white balance of the camera doesn't solve this issue.
I attached files that exemplifies the bug, shot with a Nikon D3100 with an AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6G ED II lens at 18mm focal length.
The NEF files are the original raw files, the .TIF files were obtained with ViewNX 2.7.1 with all parameters set to their default values,except for the correction of lateral chromatic aberration which was disabled and the use of a picture control with a linear tonal curve and all the other parameters (Sharpness, Saturation, Hue) set to 0. The white balance used is that of the camera, which is that for incandescent light. The _NWB.tif, _AWB.tif and _CWB.tif were obtained with Irfanview's Batch Conversion using respectively no White Balance, Automatic White Balance and Camera White Balance. The Automatic Brightness was disabled and the "Highlight mode" was set to 0. The complete image was loaded, not the preview or the half-size image as both options were disabled. The TIFF files were compressed using the LZW method:
Files DSC_0133 are from a white frame (completely saturated picture) obtained with a f/3.5 aperture, ISO 100 and 61.5 s exposure time. The channels clip at the following values:
Red:4095
Green 1:3928
Blue:4065
Green 2:3928
The images obtained with Irfanview have a slight magenta cast, whereas the image obtained with ViewNX is completely white.
Files DSC_0136 are from a white frame obtained with a f/11 aperture, ISO 100 and 82.6 s exposure time. The channels clip at the following values:
Red:4095
Green 1:3829
Blue:4095
Green 2:3840
The images obtained with Irfanview have an even more pronounced magenta cast, while the image obtained with ViewNX is completely white.
It must be noted that in both images, despite being at saturation, not all the green pixels that are not part of the border of the image reach the clipping value.
Using automatic white balance or the white balance of the camera doesn't solve this issue.
I attached files that exemplifies the bug, shot with a Nikon D3100 with an AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6G ED II lens at 18mm focal length.
The NEF files are the original raw files, the .TIF files were obtained with ViewNX 2.7.1 with all parameters set to their default values,except for the correction of lateral chromatic aberration which was disabled and the use of a picture control with a linear tonal curve and all the other parameters (Sharpness, Saturation, Hue) set to 0. The white balance used is that of the camera, which is that for incandescent light. The _NWB.tif, _AWB.tif and _CWB.tif were obtained with Irfanview's Batch Conversion using respectively no White Balance, Automatic White Balance and Camera White Balance. The Automatic Brightness was disabled and the "Highlight mode" was set to 0. The complete image was loaded, not the preview or the half-size image as both options were disabled. The TIFF files were compressed using the LZW method:
Files DSC_0133 are from a white frame (completely saturated picture) obtained with a f/3.5 aperture, ISO 100 and 61.5 s exposure time. The channels clip at the following values:
Red:4095
Green 1:3928
Blue:4065
Green 2:3928
The images obtained with Irfanview have a slight magenta cast, whereas the image obtained with ViewNX is completely white.
Files DSC_0136 are from a white frame obtained with a f/11 aperture, ISO 100 and 82.6 s exposure time. The channels clip at the following values:
Red:4095
Green 1:3829
Blue:4095
Green 2:3840
The images obtained with Irfanview have an even more pronounced magenta cast, while the image obtained with ViewNX is completely white.
It must be noted that in both images, despite being at saturation, not all the green pixels that are not part of the border of the image reach the clipping value.
