3 ms·

> It still is. It is a relatively well defined problem - removing periodic pattern due to physical arrangement of printing device. This is where algorithmic ap

by a_c 5y ago

> It still is. It is a relatively well defined problem - removing periodic pattern due to physical arrangement of printing device. This is where algorithmic approach shines over ML approach. I think nowadays a lot of ML is an attempt to outsource the problem understanding part. These are hot dogs, these are not hot dogs. I don't know what defines a hot dog, but is this picture a hot dog? Hyperbole, of course. On second thought, I think the author shouldn't remove the periodic noise at all. He was preserving "a copy of history", not the first occurrence of history. It is a property worth preserving. It is a beauty of itself imo.

II2II 5y ago
The moire is an artifact of the scanning or scaling process, and is by no means historic. Removing it is certainly legitimate. That is particularly true since scaling the image can make it worse. If you are talking about preserving the halftone in an original scan, then yes I agree that it should be preserved. Yet you must also accept that the periodic pattern will have to be removed prior to publishing the image since it will be scaled at some point.
- imoverclocked 5y ago
  It would be cool if the photo could be printed in a similar way to re-create the effect from the recovered image.
derefr 5y ago
The halftone pattern itself might look lovely and “historical” on you screen, but the book would not present the image “as-is” (i.e. with all halftone detail from the original photo losslessly captured on the page), but rather through the lens of another halftone printing process, one whose DPI is low-enough that it would arbitrarily interfere with the original photo’s to create a garbled mess. The final product wouldn’t be halftone dots encoding a picture, but rather halftone dots encoding moire stripes from an attempt to replicate other halftone dots from a “sample grid” that doesn’t line up with them. It’d be a bit like taking one of those game emulators that displays the game with a “scanline”-effect filter… and then hooking the computer running the emulator up to an old TV that has a natural built-in scanline effect. You won’t get the pretty scanlines from the emulator, nor will you get the pretty scanlines from the TV; you’ll just get a mess. (To put it in technical terms: to accurately show the halftone “information” from the original photo in the book, the print resolution of the book would need to be double the Nyquist frequency of said halftone information. But it very likely won’t be.)
- tobr 5y ago
  It would be possible to print the already halftoned image as it is without running it through another halftone process. Much like how text is not halftoned, but can include very small accurate shapes. I’m sure this makes the preproduction more complicated, but it’s essentially a software problem, not a hardware problem.
  - ralfd 5y ago
    But text is super sharp. Halftone is used to blend colors/shades.
    - tobr 5y ago
      The image is already halftoned. There are no shades left.
      - derefr 5y ago
        If you can extract the original halftone dots from the image, sure, you can create new mask layers using those. But it's unlikely that you can do that, as, unless you're printing in a four-layer pure-CMYK process (and why would you?), even the best photo scanners will be unlikely to be able to capture enough information to tease apart the original offset-layers in their original colors, where halftone dots have overlapped to produce new mixed colors. Also, you'll be unlikely to reverse the color-bleed effect of the paper to get out the original halftone dot pitch, in order to print new dots that bleed out to the same size the original's did on new, different paper with new, different inks. Basically, this is as hard as any art forgery project (i.e. needing to match historical materials and processes and environmental conditions), but before you can even start the forging process, you need to destroy even more information by passing the image through the grid-sampling process of a scanner, and only then try to reconstruct layered vector circles from the resulting sample grid.

by a_c 5y ago

II2II 5y ago

The moire is an artifact of the scanning or scaling process, and is by no means historic. Removing it is certainly legitimate. That is particularly true since scaling the image can make it worse. If you are talking about preserving the halftone in an original scan, then yes I agree that it should be preserved. Yet you must also accept that the periodic pattern will have to be removed prior to publishing the image since it will be scaled at some point.

imoverclocked 5y ago
It would be cool if the photo could be printed in a similar way to re-create the effect from the recovered image.

derefr 5y ago

The halftone pattern itself might look lovely and “historical” on you screen, but the book would not present the image “as-is” (i.e. with all halftone detail from the original photo losslessly captured on the page), but rather through the lens of another halftone printing process, one whose DPI is low-enough that it would arbitrarily interfere with the original photo’s to create a garbled mess. The final product wouldn’t be halftone dots encoding a picture, but rather halftone dots encoding moire stripes from an attempt to replicate other halftone dots from a “sample grid” that doesn’t line up with them. It’d be a bit like taking one of those game emulators that displays the game with a “scanline”-effect filter… and then hooking the computer running the emulator up to an old TV that has a natural built-in scanline effect. You won’t get the pretty scanlines from the emulator, nor will you get the pretty scanlines from the TV; you’ll just get a mess. (To put it in technical terms: to accurately show the halftone “information” from the original photo in the book, the print resolution of the book would need to be double the Nyquist frequency of said halftone information. But it very likely won’t be.)

tobr 5y ago
It would be possible to print the already halftoned image as it is without running it through another halftone process. Much like how text is not halftoned, but can include very small accurate shapes. I’m sure this makes the preproduction more complicated, but it’s essentially a software problem, not a hardware problem.
- ralfd 5y ago
  But text is super sharp. Halftone is used to blend colors/shades.
  - tobr 5y ago
    The image is already halftoned. There are no shades left.
    - derefr 5y ago
      If you can extract the original halftone dots from the image, sure, you can create new mask layers using those. But it's unlikely that you can do that, as, unless you're printing in a four-layer pure-CMYK process (and why would you?), even the best photo scanners will be unlikely to be able to capture enough information to tease apart the original offset-layers in their original colors, where halftone dots have overlapped to produce new mixed colors. Also, you'll be unlikely to reverse the color-bleed effect of the paper to get out the original halftone dot pitch, in order to print new dots that bleed out to the same size the original's did on new, different paper with new, different inks. Basically, this is as hard as any art forgery project (i.e. needing to match historical materials and processes and environmental conditions), but before you can even start the forging process, you need to destroy even more information by passing the image through the grid-sampling process of a scanner, and only then try to reconstruct layered vector circles from the resulting sample grid.