Emil Martinec
New member
I often see statements about one or another DSLR's exhibiting good (or bad) quality of the "noise grain" in their images, or that model A has better "noise grain" than model B. Imatest can spit out a measure of noise as a function of spatial frequency to try to quantify this.
My question is, why should there be such a difference, unless it is introduced by differences in the raw conversion being used? If we are talking about noise in midtones and highlights, that is dominated by photon shot noise which is purely white as a function of spatial frequency; it cannot differ from one camera to another as long as the raw data are raw and losslessly encoded. There can be a difference in shadows, since read noise can vary from camera to camera and contain more or less banding etc; though if we are talking about the grain aspect of noise rather than banding, that too is spatially white and my question still stands. So why is the "noise grain" a property of the camera and not the raw converter?
Of course there might be differences when viewing the full frame image due to differences in megapixel count, but I presume people are making these judgments by viewing the image at 100%, where the playing field should be level.
Any ideas?
My question is, why should there be such a difference, unless it is introduced by differences in the raw conversion being used? If we are talking about noise in midtones and highlights, that is dominated by photon shot noise which is purely white as a function of spatial frequency; it cannot differ from one camera to another as long as the raw data are raw and losslessly encoded. There can be a difference in shadows, since read noise can vary from camera to camera and contain more or less banding etc; though if we are talking about the grain aspect of noise rather than banding, that too is spatially white and my question still stands. So why is the "noise grain" a property of the camera and not the raw converter?
Of course there might be differences when viewing the full frame image due to differences in megapixel count, but I presume people are making these judgments by viewing the image at 100%, where the playing field should be level.
Any ideas?