5 ms·

I have a related anecdote. When I worked at Amazon on the Kindle Special Offers team (ads on your eink Kindle while it was sleeping), the first implementation

by delecti 10mo ago

I have a related anecdote. When I worked at Amazon on the Kindle Special Offers team (ads on your eink Kindle while it was sleeping), the first implementation of auto-generated ads was by someone who didn't know that properly converting RGB to grayscale was a smidge more complicated than just averaging the RGB channels. So for ~6 months in 2015ish, you may have seen a bunch of ads that looked pretty rough. I think I just needed to add a flag to the FFmpeg call to get it to convert RGB to luminance before mapping it to the 4-bit grayscale needed.

barishnamazov 10mo ago
I don't think Kindle ads were available in my region in 2015 because I don't remember seeing these back then, but you're a lucky one to fix this classic mistake :-) I remember trying out some of the home-made methods while I was implementing a creative work section for a school assignment. It’s surprising how "flat" the basic average looks until you actually respect the coefficients (usually some flavor of 0.21R + 0.72G + 0.07B). I bet it's even more apparent in a 4-bit display.
- reactordev 10mo ago
  If you really want that old school NTSC look: 0.3R + 0.59G + 0.11B This is the coefficients I use regularly.
  - ycombiredd 10mo ago
    Interesting that the "NTSC" look you describe is essentially rounded versions of the coefficients quoted in the comment mentioning ppm2pgm. I don't know the lineage of the values you used of course, but I found it interesting nonetheless. I imagine we'll never know, but it would be cool to be able to trace the path that lead to their formula, as well as the path to you arriving at yours
    - reactordev 10mo ago
      I’m sure it has its roots in amiga or TV broadcasting. ppm2pgm is old school too so we all tended to use the same defaults. Like q3_sqrt
    - zinekeller 10mo ago
      The NTSC color coefficients are the grandfather of all luminance coefficients. It is necessary that it was precisely defined because of the requirements of backwards-compatible color transmission (YIQ is the common abbreviation for the NTSC color space, I being ~reddish and Q being ~blueish), basically they treated B&W (technically monochrome) pictures like how B&W film and videotubes treated them: great in green, average in red, and poorly in blue. A bit unrelated: pre-color transition, the makeups used are actually slightly greenish too (which appears nicely in monochrome).
      - shagie 10mo ago
        To the "the grandfather of all luminance coefficients" ... https://www.earlytelevision.org/pdf/ntsc_signal_specifications.pdf https://www.earlytelevision.org/pdf/ntsc_signal_specificatio... from 1953. Page 5 has: Eq' = 0.41 (Eb' - Ey') + 0.48 (Er' - Ey') Ei' = -0.27(Eb' - Ey') + 0.74 (Er' - Ey') Ey' = 0.30Er' + 0.59Eg' + 0.11Eb' The last equation are those coefficients.
        zinekeller 10mo ago
        I was actually researching why PAL YUV has the same(-ish) coefficients, while forgetting that PAL is essentially a refinement of the NTSC color standard (PAL stands for phase-alternating line, which solves much of NTSC's color drift issues early in its life).
        adrian_b 10mo ago
        It is the choice of the 3 primary colors and of the white point which determines the coefficients. PAL and SECAM use different color primaries than the original NTSC, and a different white, which lead to different coefficients. However, the original color primaries and white used by NTSC had become obsolete very quickly so they no longer corresponded with what the TV sets could actually reproduce. Eventually even for NTSC a set of primary colors was used that was close to that of PAL/SECAM, which was much later standardized by SMPTE in 1987. The NTSC broadcast signal continued to use the original formula, for backwards compatibility, but the equipment processed the colors according to the updated primaries. In 1990, Rec. 709 has standardized a set of primaries intermediate between those of PAL/SECAM and of SMPTE, which was later also adopted by sRGB.
  - JKCalhoun 10mo ago
    Yep, used in the early MacOS color picker as well when displaying greyscale from RGB values. The three weights (which of course add to 1.0) clearly show a preference for the green channel for luminosity (as was discussed in the article).
- kccqzy 10mo ago
  I remember using some photo editing software (Aperture I think) that would allow you to customize the different coefficients and there were even presets that give different names to different coefficients. Ultimately you can pick any coefficients you want, and only your eyes can judge how nice they are.
  - acomjean 10mo ago
    >Ultimately you can pick any coefficients you want, and only your eyes can judge how nice they are. I went to a photoshop conference. There was a session on converting color to black and white. Basically at the end the presenter said you try a bunch of ways and pick the one that looks best. (people there were really looking for the “one true way”) I shot a lot of black and white film in college for our paper. One of my obsolete skills was thinking how an image would look in black and white while shooting, though I never understood the people who could look at a scene and decide to use a red filter..
    - jnovek 10mo ago
      This is actually a real bother to me with digital — I can never get a digital photo to follow the same B&W sensitivity curve as I had with film so I can never digitally reproduce what I “saw” when I took the photo.
      - marssaxman 10mo ago
        Film still exists, and the hardware is cheap now! I am shooting a lot of 120-format Ilford HP5+ these days. It's a different pace, a different way of thinking about the craft.
    - Grimm665 10mo ago
      > I shot a lot of black and white film in college for our paper. One of my obsolete skills was thinking how an image would look in black and white while shooting, though I never understood the people who could look at a scene and decide to use a red filter.. Dark skies and dramatic clouds! https://i.ibb.co/0RQmbBhJ/05.jpg https://i.ibb.co/0RQmbBhJ/05.jpg (shot on Rollei Superpan with a red filter and developed at home)
isoprophlex 10mo ago
I wouldn't worry about it too much, looking at ads is always a shitty experience. Correctly grayscaled or not.
- wolvoleo 10mo ago
  True, though in the case of the Kindle they're not really intrusive (only appearing when it's off) and the price to remove them is pretty reasonable ($10 to remove them forever IIRC). As far as ads go that's not bad IMO)
  - marxisttemp 10mo ago
    The price of an ad-free original kindle experience was $409. The $10 is on top of the price the user paid for the device.
    - delecti 10mo ago
      Lets not distort the past. The ads were introduced a few years later with the Kindle Keyboard, which launched with an MSRP of $140 for the base model, or $115 with ads. That was a substantial discount on a product which was already cheap when it released. All for ads which are only visible when you aren't using the device anyway. Don't like them? Then buy other devices, pay to have them removed, get a cover to hide them, or just store it with the screen facing down when you aren't using it.
      - wolvoleo 10mo ago
        Yes and here in Europe they were introduced even later, with kindle 4 IIRC.
  - account42 9mo ago
    Sure, and piss doesn't taste quite as bad as shit yet I still don't want it in my food.

by delecti 10mo ago

barishnamazov 10mo ago

I don't think Kindle ads were available in my region in 2015 because I don't remember seeing these back then, but you're a lucky one to fix this classic mistake :-) I remember trying out some of the home-made methods while I was implementing a creative work section for a school assignment. It’s surprising how "flat" the basic average looks until you actually respect the coefficients (usually some flavor of 0.21R + 0.72G + 0.07B). I bet it's even more apparent in a 4-bit display.

reactordev 10mo ago
If you really want that old school NTSC look: 0.3R + 0.59G + 0.11B This is the coefficients I use regularly.
- ycombiredd 10mo ago
  Interesting that the "NTSC" look you describe is essentially rounded versions of the coefficients quoted in the comment mentioning ppm2pgm. I don't know the lineage of the values you used of course, but I found it interesting nonetheless. I imagine we'll never know, but it would be cool to be able to trace the path that lead to their formula, as well as the path to you arriving at yours
  - reactordev 10mo ago
    I’m sure it has its roots in amiga or TV broadcasting. ppm2pgm is old school too so we all tended to use the same defaults. Like q3_sqrt
  - zinekeller 10mo ago
    The NTSC color coefficients are the grandfather of all luminance coefficients. It is necessary that it was precisely defined because of the requirements of backwards-compatible color transmission (YIQ is the common abbreviation for the NTSC color space, I being ~reddish and Q being ~blueish), basically they treated B&W (technically monochrome) pictures like how B&W film and videotubes treated them: great in green, average in red, and poorly in blue. A bit unrelated: pre-color transition, the makeups used are actually slightly greenish too (which appears nicely in monochrome).
    - shagie 10mo ago
      To the "the grandfather of all luminance coefficients" ... https://www.earlytelevision.org/pdf/ntsc_signal_specifications.pdf https://www.earlytelevision.org/pdf/ntsc_signal_specificatio... from 1953. Page 5 has: Eq' = 0.41 (Eb' - Ey') + 0.48 (Er' - Ey') Ei' = -0.27(Eb' - Ey') + 0.74 (Er' - Ey') Ey' = 0.30Er' + 0.59Eg' + 0.11Eb' The last equation are those coefficients.
      - zinekeller 10mo ago
        I was actually researching why PAL YUV has the same(-ish) coefficients, while forgetting that PAL is essentially a refinement of the NTSC color standard (PAL stands for phase-alternating line, which solves much of NTSC's color drift issues early in its life).
        adrian_b 10mo ago
        It is the choice of the 3 primary colors and of the white point which determines the coefficients. PAL and SECAM use different color primaries than the original NTSC, and a different white, which lead to different coefficients. However, the original color primaries and white used by NTSC had become obsolete very quickly so they no longer corresponded with what the TV sets could actually reproduce. Eventually even for NTSC a set of primary colors was used that was close to that of PAL/SECAM, which was much later standardized by SMPTE in 1987. The NTSC broadcast signal continued to use the original formula, for backwards compatibility, but the equipment processed the colors according to the updated primaries. In 1990, Rec. 709 has standardized a set of primaries intermediate between those of PAL/SECAM and of SMPTE, which was later also adopted by sRGB.
- JKCalhoun 10mo ago
  Yep, used in the early MacOS color picker as well when displaying greyscale from RGB values. The three weights (which of course add to 1.0) clearly show a preference for the green channel for luminosity (as was discussed in the article).
kccqzy 10mo ago
I remember using some photo editing software (Aperture I think) that would allow you to customize the different coefficients and there were even presets that give different names to different coefficients. Ultimately you can pick any coefficients you want, and only your eyes can judge how nice they are.
- acomjean 10mo ago
  >Ultimately you can pick any coefficients you want, and only your eyes can judge how nice they are. I went to a photoshop conference. There was a session on converting color to black and white. Basically at the end the presenter said you try a bunch of ways and pick the one that looks best. (people there were really looking for the “one true way”) I shot a lot of black and white film in college for our paper. One of my obsolete skills was thinking how an image would look in black and white while shooting, though I never understood the people who could look at a scene and decide to use a red filter..
  - jnovek 10mo ago
    This is actually a real bother to me with digital — I can never get a digital photo to follow the same B&W sensitivity curve as I had with film so I can never digitally reproduce what I “saw” when I took the photo.
    - marssaxman 10mo ago
      Film still exists, and the hardware is cheap now! I am shooting a lot of 120-format Ilford HP5+ these days. It's a different pace, a different way of thinking about the craft.
  - Grimm665 10mo ago
    > I shot a lot of black and white film in college for our paper. One of my obsolete skills was thinking how an image would look in black and white while shooting, though I never understood the people who could look at a scene and decide to use a red filter.. Dark skies and dramatic clouds! https://i.ibb.co/0RQmbBhJ/05.jpg https://i.ibb.co/0RQmbBhJ/05.jpg (shot on Rollei Superpan with a red filter and developed at home)

isoprophlex 10mo ago

I wouldn't worry about it too much, looking at ads is always a shitty experience. Correctly grayscaled or not.

wolvoleo 10mo ago
True, though in the case of the Kindle they're not really intrusive (only appearing when it's off) and the price to remove them is pretty reasonable ($10 to remove them forever IIRC). As far as ads go that's not bad IMO)
- marxisttemp 10mo ago
  The price of an ad-free original kindle experience was $409. The $10 is on top of the price the user paid for the device.
  - delecti 10mo ago
    Lets not distort the past. The ads were introduced a few years later with the Kindle Keyboard, which launched with an MSRP of $140 for the base model, or $115 with ads. That was a substantial discount on a product which was already cheap when it released. All for ads which are only visible when you aren't using the device anyway. Don't like them? Then buy other devices, pay to have them removed, get a cover to hide them, or just store it with the screen facing down when you aren't using it.
    - wolvoleo 10mo ago
      Yes and here in Europe they were introduced even later, with kindle 4 IIRC.
- account42 9mo ago
  Sure, and piss doesn't taste quite as bad as shit yet I still don't want it in my food.