James writes: : It seems that 'blooming' in a film camera can occur when the light : intensity in an area is such that the adjacent areas get some of the : photons that are not absorbed by the silver crystals. For this to : happen in a digital camera, the individual pixel sensors would have : to have at least semi-transparent walls that allowed reflected light : to pass to adjacent sensors. To get significant 'blooming', the : light intensity would have to be such that the adjacent sensors would : pass it on, so to speak. : : Does anyone know if the side walls on image pixel sensors are at all : transparent or not? : : For 'haloing' to occur in a digital camera, the software that does : the interpolation to fill in the missing colors and adjusts the : contrast could easily do this. You get the same effect by over : sharpening in the image processing software. I'm not aware of a : process that yields haloing in a film camera while the film is still : in the camera. Help me if someone on the list does know how this might happen/ : more from that page link I first quoted from: "To prevent blooming, some cameras are equipped with "anti-blooming gates" that prevent the overflow of photon data from ruining the picture. However, the anti-blooming gate feature can only minimize blooming if the scene isn't set in a brightly lit area" on another page <http://alignment.hep.brandeis.edu/Electronics/A2056/M2056.html> they show images of a digital sensor swamped and exhibiting 'blooming' as they call it here <http://www.ccd.com/ccd102.html> they discuss the effect of both using and not using an 'anti-blooming gate' on sensors "Blooming vs. Anti-Blooming "An example of blooming Some sensors, including the Kodak KAF series, offer an optional anti-blooming gate designed to bleed off overflow from a saturated pixel. Without this feature, a bright star which has saturated the pixels (much greater than 85,000 electrons) will cause a vertical streak. This can be irritating at best, and if the streak bleeds onto your target object, there is no way to recover the lost data. CCDs with Anti-blooming gate protection are NOT recommended for low light level work because of the reduced sensitivity of these devices IF a better option is available. " karl
