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Is it true that Canon sensors have half the number of colors than Nikon, Fujifilm or Sony sensors? I read this on Quora.

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    Abraham Lincoln once said: Do not trust everything you read on the internet Aug 24, 2021 at 5:13
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    Each bit multiplies the number of colors by 8 (2^3, because there are 3 colors). Since most people are still using 8-bit (or lower) displays, 10-14-bits is more than enough. Technology is always advancing, and companies tend to play leapfrog with their competitors. So what was true yesterday isn't necessarily true today.
    – xiota
    Aug 24, 2021 at 5:37
  • @xiota You comment doesn't answer the question. Do you mean each pixel instead of each bit? Aug 24, 2021 at 6:03
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    @xiota means bits. With N bits you can encode 2^N values, in other words measure 2^N values in a "sensel". Sensors are between 12 to 16 bits. With 12 bits you can encode 4096 levels (2¹²), with 14, 16384 (2¹⁴), and with 16, 65536 (2¹⁶). So a sensor with more bits per "sensel" can theoretically give more information. However with more bits the additional bits are mostly in the noise area, so cost you processing power without adding much information. BTW if you add 1 bit to the sensor, you multiply the number of final colors by 8 (because you have doubled each of the three channels), not by 2.
    – xenoid
    Aug 24, 2021 at 6:58
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    Colors are represented in bits. Each extra bit doubles the number of values that can be represented. Adding a bit to each color adds three bits total because there are three colors. An 8-bit color representation supports 256 values for each color primary. About 16.7M colors total. 10-bits = 1.1B colors. 12-bits = 68B colors. 14-bits = 4.4T colors. If you're using JPG, you're stuck with 8-bits. If you're using RAW with any reasonably modern camera, you have more than enough colors, regardless of the camera manufacturer.
    – xiota
    Aug 24, 2021 at 6:58

1 Answer 1

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It is not true as a general statement.

The statement seems to be a confusion as to how Canon's "dual pixel autofocus" works (a feature of most modern Canon DSLR's)... The dual pixel phase detection autofocus system combines two sensor photodiodes (sensor/AF "pixels") as a single image pixel; thereby reducing the potential color separation/sensitivity by half compared to if the sensor photodiodes were filtered/recorded separately.

The (potential) issue/misunderstanding here is due to Canon's use of common terminology and calling sensor photosites/photodiodes pixels... which isn't really the case.

It might be true in comparing two specific cameras where the Canon is recording images at a lower bit depth (e.g. only records jpegs), or the Canon has lower color sensitivity at a given ISO. But that is also dependent on the specific cameras being compared. I.e. the Canon 7D is ~ 1-2 bit lower than the Nikon D800 at any ISO; but the 5D Mk4 is pretty much equal to the D800 at all ISO's (each bit is 2x, but 2 bit here is less than 1 bit/color).

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  • Do you mean to say Canon employs two sensors, one for autofocus and another for just image capture, and the one it uses for autofocus combines to two photodiodes/photosites into one pixel, and that answerer on Quora confused the both. Aug 26, 2021 at 1:01
  • No, it's one sensor that does both jobs. When autofocusing the two photodiodes (per site/color filter) are kept separate and function like a split prism viewfinder. Then when the image is recorded the two are combined as a single pixel. The problem is everyone calls sensor photodiodes pixels (the aren't really) and Canon confused it more by claiming two pixels for autofocus are combined as one pixel in output. Pixel stands for "picture element" and you cannot combine two as one without loosing resolution (color data). slrlounge.com/camera-tech-explained-canon-dual-pixel-autofocus Aug 26, 2021 at 13:07

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