I'm James Hague, a recovering programmer who has been designing video games since the 1980s. This is Why You Spent All that Time Learning to Program and The Pure Tech Side is the Dark Side are good places to start.
Where are the comments?
Common Sense, Part 1
There's a photo of mine in the September 2010 issue of Popular Photography. I'm excited about it; my photo credits are few and far between, and it brings back the feelings I had when I wrote for magazines long ago. Completely ignoring the subject of the image, there are couple of surprising facts about it.
The first is that it was a taken on a circa-2004 Canon PowerShot G5, a camera with a maximum resolution of five megapixels.
The second is that it's a doubly-compressed JPEG. The original photo was a JPEG, then I adjusted the colors and contrast a bit, and saved it out as a new JPEG. Each save lost some of the image quality. I was perfectly willing to submit the adjusted photo as a giant TIFF to avoid that second compression step, but was told not to worry about it; the JPEG would be fine.
Yet there it is: the five megapixel, doubly-compressed photo, printed across almost two pages of the magazine. And those two technical facts are irrelevant. I can't tell the difference; it looks great in print.
Now it is an impressionistic shot, so it could just be that the technical flaws aren't noticeable in this case. Fortunately, I have another anecdote to back it up.
Last year I was in New Mexico and took a lot of photos. After I got back home, I decided to get a few photo books printed. The source images were all twelve megapixel JPEGs, but the book layout software recommended a six megapixel limit. I cut the resolution in half, again twice-compressing them. When I got the finished books back, the full-page photos were sharp and beautiful.
The standard, pedantic advice about printing photos is that resolution is everything. Shoot as high as possible. Better yet, save everything as RAW files, so there's no lossy compression. Any JPEG compression below maximum is unacceptable. Double-compression is an error of the highest order, one only made by rank amateurs. And so it goes. But I know from personal experience that while it sounds authoritative, and while it's most likely given in a well-meaning manner, it's advice that's endlessly repeated in a loose, "how could it possibly be wrong?" sort of way and never actually tested.