How is a JPEG image’s color type determined?

In order to decode and display a JPEG image, you have to know what "color type" (or "color model") it uses. There are several possibilities that your software probably ought to handle: Grayscale YCbCr (transformed from RGB) RGB YCCK (transformed from CMYK) CMYK Unfortunately, if you look at all the bits and bytes that make …

Large prime numbers

As of this writing, the largest known prime number is 277232917-1. "Not large enough!", I say. Let's write a computer program that will print out a larger prime number. No, not a program that will take billions of years to run. It should take only a few minutes. There is a small catch. Hardly worth …

Summary of some Win32 I/O character encoding behavior

This post is about programming a Windows Win32 application, mainly one that uses the console (command line). It summarizes the results of some tests I performed. Maybe you ported a Unix utility to Windows, but you find that it doesn't work with filenames that contain Japanese characters. This information may help, though specific recommendations will …