4 ms·

Red, green, and blue have been scaled by .2126, .7152, and .0722, which add up to 1.0 exactly (even in single-precision float), and if those values really were

Red, green, and blue have been scaled by .2126, .7152, and .0722, which add up to 1.0 exactly (even in single-precision float), and if those values really were all in [0,255] range, the maximum value that could be produced by this math is only 254, due to rounding. I think what's happening here is that the image is in a format that's holding those original red, green, and blue values in a format that can hold values outside logical [0,1]. Update: sorry, the comment below me doesn't seem to have a 'respond' link so I'll just edit one in here. I totally agree with you it's good practice to document your invariants in code, but in practice it would result in the same thing... an unhandled failure with nothing better to do than crash the process. In a way (if you squint) indexing into an array of size 256 is itself documenting the invariant that the index is less than 256. It's just that the invariant itself is wrong.

jeffbee 6y ago
On my planet we write those invariants in code, such as CHECK(Color.red(pixel) < 55); Or whatever.
- gruez 6y ago
  You mean an assertion? I'm not sure how that would help. The code is still going to crash, and unless you tested for that specific case, it's not going to show up in testing either.
jeffbee 6y ago
Replying to your update: the reason you write out the invariants is then it becomes perfectly obvious in code review that the method only works for certain images and isn't protected against being called with unusable images, at which point the review can say "don't land this". Truth in advertising. If this had been named "getHistogramOfSRGBBitmapElseOOBE" nobody would have stamped it because that's obviously dumb.
JadeNB 6y ago
> sorry, the comment below me doesn't seem to have a 'respond' link so I'll just edit one in here. For future reference: I'll often see that for a post in the context of a larger thread, but the 'reply' link has always appeared when I navigate to the post itself (by clicking on the timestamp). Maybe you already tried that, though.

jeffbee 6y ago

On my planet we write those invariants in code, such as CHECK(Color.red(pixel) < 55); Or whatever.

gruez 6y ago
You mean an assertion? I'm not sure how that would help. The code is still going to crash, and unless you tested for that specific case, it's not going to show up in testing either.

jeffbee 6y ago

Replying to your update: the reason you write out the invariants is then it becomes perfectly obvious in code review that the method only works for certain images and isn't protected against being called with unusable images, at which point the review can say "don't land this". Truth in advertising. If this had been named "getHistogramOfSRGBBitmapElseOOBE" nobody would have stamped it because that's obviously dumb.

JadeNB 6y ago

> sorry, the comment below me doesn't seem to have a 'respond' link so I'll just edit one in here. For future reference: I'll often see that for a post in the context of a larger thread, but the 'reply' link has always appeared when I navigate to the post itself (by clicking on the timestamp). Maybe you already tried that, though.