I ran the FFT analysis of yesterday’s post on a couple of more images. First, this old chestnut (thank you, Fuji): Here’s what I got: For the last three octaves of spatial frequency, the two chromaticity components are about the same distance below the luminance component. Then there’s this image (thank you again, Fuji): Here’s… [Read More]
Archives for April 2014
Luminance and chromaticity vs spatial frequency
There was a great thread on the dpreview forum started by Jack Hogan (who has also posted in this blog), about anisotropy in anti-aliasing filters. In the generally erudite and productive discussion that followed, someone (I’d give him credit, but I don’t know his real name) made these comments about demosacing: From a reconstruction perspective,… [Read More]
Color photography without demosaicing in the real world
Today I continue exploring using a technique to produce half-sized images from sensors with Bayer color filter arrays (CFAs). The technique was described here, and the way I’m implementing it was explained here. I started with a raw file of this scene, photographed with the Sony a7R and the Sony/Zeiss 55mm f/1.8 Sonnar FE (aka… [Read More]
Color photography without demosaicing in practice
Yesterday’s post trotted out an idea for producing moderate resolution files from high-resolution cameras without demosaicing, and speculated that such files might show higher quality and fewer artifacts than similar-sized filed down-res’d from demosaiced raw files. I looked around for a tool to perform an experiment. I didn’t have to look far. DCRAW has an… [Read More]
Color photography without demosaicing
In the beginning, digital photography sensors were monochromatic. If you wanted color, you made three successive exposures through different filters, which were usually mounted on a wheel for rapid sequencing. A variant of this approach was to use a series of prisms and half-silvered mirrors to split the imaging light into three beams which were… [Read More]