Yesterday I reported on the amount of noise, and the spectra, of noisy test images exported from Lightroom with sharpening turned off. Today we’ll see what happens when it’s set. Here’s the test protocol. The target image is a 4000×4000 sRGB, with each plane filled with a constant signal of half-scale, (0.5, 127.5, or 32767.5,… [Read More]

In the last two posts, I delved into how well Photoshop (Ps) does in minimizing photon noise when downsizing images using bilinear and bicubic sharper interpolation. Today I’m turning my attention to Lightroom (Lr). With Lr, you don’t get to choose your resampling algorithm or the gamma of the space in which Lr does the… [Read More]

Same test image as yesterday 4000×4000 monochromatic, 16-bit gray gamma 2.2, filled with a constant signal of half-scale, (0.5, 127.5, or 32767.5, depending on how you think of it), with Gaussian noise with standard deviation of 1/10 scale added to it. The image was created in Matlab, written out as a 16-bit TIFF, read into… [Read More]

When I last left you, the jury was out on the issue of whether the bilinear interpolation downsizing algorithm in Photoshop was the same as the one in Matlab. The jury is back. “Mr. Foreman, have the jury reached a verdict?” “We have, your honor.” “May I hear it?” “The algorithms are wildly different, as… [Read More]

In the two previous posts, I identified some anomalies with Matlab’s implementation of bilinear interpolation downsampling at reduction ratios that are integral powers of two. I also observed smaller, but similar, anomalies with bicubic, Lanczos 2, and Lanczos 3 downsampling. Today I set out to find out if the Photoshop implementations of bilinear interpolation evinced… [Read More]