Eisenstein 3 days ago

"Zoom into this image so that the width of each vertical line is 1 mm or the whole image is 3.2 inches wide."

Is it possible to pick one system? Also, "3.2 inches" is difficult to measure. Rulers that measure in less than an inch use fractions, not decimals. It usually goes by 1/8ths, then 1/4 and 1/2, but some rulers have 1/16ths. 3/16" is .187 inches which is pretty close I guess.

  • funac 3 days ago

    > "Zoom into this image so that the width of each vertical line is 1 mm or the whole image is 3.2 inches wide." > > Is it possible to pick one system? Also, "3.2 inches" is difficult to measure. Rulers that measure in less than an inch use fractions, not decimals. It usually goes by 1/8ths, then 1/4 and 1/2, but some rulers have 1/16ths. 3/16" is .187 inches which is pretty close I guess.

    decimal inch rulers (& tape measures) are available; i have several. imo they're much more useful than fractional rulers in the context of machining, where the natural base unit, if you're not in metric, is 0.001” ('one thou')

dsign 4 days ago

Half-in-jest, I think we should put some pressure on the International Bureau of Weights and Measures to standardize dots per meter (DPM), and then have the EU follow through with a new law or two to accelerate adoption.

perching_aix 3 days ago

Unfortunately printers print in dots though, not pixels. There are printers with variable dot sizes, supposedly a thing with professional print, I wouldn't know - but nominally a dot is gonna be one of the four ink colors (cyan, magenta, yellow, black) and then it's either present or not present. I'm sure someone who didn't sleep only just one hour overnight can calculate you how many dots you need to cover the same gamut as a typical 24 bit SDR RGB pixel will.

aaronbrethorst 4 days ago

tl;dr:

    Viewing distance PPI
    1 meter          170 pixels/inch
which is to say that a 12mp image is going to max out at 18x24"
  • alwa 4 days ago

    …supposing the pixels are the limiting factor, and that you’re interested in viewing an 18x24” image from 3 feet away.

    If the optics that captured the image are such that its sharpest feature spans multiple pixels, TFA provides some handy rules of thumb to adjust your print size down accordingly.