Since film is all about analogue chemicals, clipping on it is a smooth transition for any colour from a given exposure to pure white. Sometimes it's easy to recognize a digital landscape just by looking at the wrong colours surrounding the sun, try it. This is one of the disadvantages of digital.
I think we cannot call this a problem of DR, but of how the highlights reach saturation: progressively in film, suddendly on each RGB channel in digital.
BR
Guillermo's post raises some interesting aspects of digital imaging and white balance.
The spectral response of a sensor can be determined with scientific equipment, as shown in a
post from Stanford University, reproduced there under fair use copyright. The study is for the Nikon D70 and shows that the sensor is most sensitive to green, followed by blue and then red.
[attachment=16517:D70_spec...response.png]
If you take a picture of a white reflector with the D70, the RGB response will be determined by the amounts of red, blue, and green in the illumination and the spectral response of the sensor. Daylight has relatively equal amounts of red, blue and green as shown in this spectral analysis on the
General Electric Lighting Web Site.
[attachment=16518:daylightSpectrum.png]
To determine the camera response, one must convolve the spectral response of the camera with the spectral composition of the daylight. For example, with green one would divide the camera response of the green channel into small ranges, perhaps at 10 nm intervals (bands). One would do the same with the daylight spectrum and then multiply the radiance in each band by the response of the camera.
This image shows a shot of a MacBeth color checker photographed in daylight with the D70 without any white balance. The histogram shows relative exposures of the channels. To apply white balance, the red and blue channels are multiplied by white balance coefficients such that the exposures are equalized. In the raw file, green is blown first, followed by blue and then red.
[attachment=16519:D70_raw_daylight.png]
If you photograph the target under tungsten light, you get a quite different response since tungsten is quite deficient in blue as shown in the SPD of tungsten illumination. With tungsten and the D70, green blows first, followed by red and rather distantly by blue.
[attachment=16520:D70_raw_tungsten.png]
[attachment=16521:TungstenSpectrum.png]
Now to Guillermo's picture. The disc of the sun is completely blown and all pixel values will be white, RGB = 255, 255, 255
As one moves away from the disc, the radiance decreases and color shifts are introduced as shown in the histogram below. At the indicated sampling point, the green and red are near saturation and the blue is below clipping. The result is yellow.
[attachment=16522:blownSunset.png]
When channels are blown with a digital sensor, there will be color shifts due to unequal sensitivities of the sensor to red, blue, and green as shown.
If the spectral responses of the sensor were equal for all colors at the given illuminant, there would be no color shift. Since transparency film is color balanced for the illuminant, it does not suffer this shift. One could put a filter over the camera lens with a digital camera so as to equalize the channels and avoid the shifts. Due to nonlinearity with clipping, this would be difficult to do in post, just as color balancing an image taken under tungsten illumination with daylight Kodachrome is difficult.
