alt Hacker NewssRGB has bugged me from the start, since it's not even clear to me which actual matrix to use to convert between linear sRGB colors and XYZ colors. I count at least 3 different matrices in IEC 61966-2-1, each of which I have seen different people ascribe to as the true version:
1. The matrix implied by the reference primaries in Table 1: [X; Y; Z] = [506752/1228815, 87098/409605, 7918/409605; 87881/245763, 175762/245763, 87881/737289; 12673/70218, 12673/175545, 1001167/1053270]*[R; G; B].
2. The matrix in section 5.2: [X; Y; Z] = [1031/2500, 447/1250, 361/2000; 1063/5000, 447/625, 361/5000; 193/10000, 149/1250, 1901/2000]*[R; G; B].
3. The inverse of the matrix in section 5.3: [X; Y; Z] = [248898325000/603542646087, 71938950000/201180882029, 36311670000/201180882029; 128304856250/603542646087, 143878592500/201180882029, 14525360000/201180882029; 11646692500/603542646087, 23977515000/201180882029, 191221850000/201180882029]*[R; G; B].
The distinction starts to matter for 16-bit color. The CSS people seem to take the position that the matrix implied by primaries is the true version, but meanwhile, the same document's Annex F (in Amd. 1) seems to suggest that the 5.2 matrix is the true version, and that the 5.3 matrix should be rederived to the increased precision. There's no easy way to decide, as far as I can tell.
Meanwhile, I agree with the author that the ICC's black-point finagling in their published profiles has not helped with the confusion over what exactly sRGB colors are supposed to map to.
It's perfectly fine for fingerprinting though. Innocuous artifacts in file formats such as custom matrices, digits on the seventh decimal position of a floating point number or millisecond-precision timestamps allow identification and cross-referencing of internet users.
Just last week I noticed that when a reddit user uploads a screenshot taken on MacOS as PNG image to a reddit post, the PNG will still contain uniquely identifying information about the monitor that is attached to the MacOS system and when it was last calibrated. You can deduce type of Macbook they are using from the screen resolution and see when they switched machines once you notice a different monitor calibration timestamp. Just from a single PNG image that was uploaded by the user themselves. If those two pieces of information are not stored in the PNG you know that they must be Windows or Linux user.
It's these small breadcrumbs all over the place which make forensics so interesting.