Photoshop: Support 24 bits per primary color - including alpha channel, 24*4=96bits

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support 24 bits per primary color - including alpha channel, 24*4=96bits. there are ADC's (analog-to-digital converters) that handle this many bits, so why not?
I heard ps only supports 32-bit color, if that's total bits, that's 8 bits per primary color + 8 alpha (8:8:8:8). this would be 24:24:24:24.
total number of bytes for uncompressed image would be ceil(24bppPerPrimaryColor*4/8bitsPerByte*x*y)=bytes
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Chris Cox

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You seem to be confusing bits per channel with total bits. The total bits is a useless number, because it does't indicate the number of channels and can be achieved by multiple combinations. For instance, is 32 bits: 1 channel of 32 bits, 2 channels of 16 bits, or 4 channels of 8 bits? This is why professionals use bits/channel to describe file formats and images, not total bits.
Photoshop supports 1, 8, 16 and 32 bits/channel images in many color models.
(between 1 and 128 bits total :-) ). Photoshop will promote files with intermediate bits to the next higher supported mode (i.e.: 2,3,4,5,6,7 bits/channel -> 8 bits/channel, 10,...,15 bits/channel -> 16 bit/channel).

You also seem to be confusing alpha channels with transparency. Alpha channels are any additional channels beyond the color data (selections, rough mattes, comments, depth maps, antialiasing maps, coverage maps, specular maps, bump maps, etc.). The transparency/opacity is a subset of alpha channels, tightly coupled with the color channels, with a specific definition. You can have many alpha channels in an image, but only one transparency/opacity channel.
Photoshop has supported transparency since version 3.0 in 1994.

You might want to take a look at the Photoshop online documentation for a better understanding of image depths, modes, transparency, and alpha channels. Start here:

While DACs & ADCs (Digital to Analog Converters & Analog to Digital Converts for non-EE types) exist for a higher number of bits, video cards don't currently support that many bits/channel in an output frame buffer, and common displays max out at 10 bits/channel (there are some 12 and 16 bit/channel displays for specialized use, but not widespread). We do work closely with the GPU and display manufacturers to support the new technologies as they become available.