the last word

I got some perceptive comments about the resampling post, all from the same person. Here’s the first: For starters, two-thirds (not half) of the information in any color image from a Bayer-pattern sensor is fabricated.  Half of the green and three-quarters each of the red and blue pixel values are made up. Absolutely true. My… [Read More]

Resampling has a bad name among many photographers. Here’s a typical pronouncement,  from here: “I am not going to address resampling here because it degrades an image and has little application in fine art photography. (Resampling is when Photoshop adds pixels to an image.)” Dodgy grammar aside, I strongly disagree. On the artistic level, I… [Read More]

Let’s review conventional sampling theory. We start with a continuous representation (the real world, as imaged by the lens), filter that to remove spectral components above half the sampling frequency, sample at evenly spaced infinitesimal points, digitize the results, and store them. To reconstruct the input we take the samples, recreate their values and locations,… [Read More]

I’ve had some email on the antialiasing posts. One person quotes me from Antialiasing, part 2 as follows: The good news is that increasing the area of the sensor receptors reduces aliasing, and does it fairly efficiently. William Pratt, in his book Digital Image Processing, 2nd Edition, on pages 110 and 111, compares a square receptor… [Read More]