A7iii vs A7Riii

Started 2 months ago | Discussions thread
SafariBob Contributing Member • Posts: 835
Re: A7iii vs A7Riii

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

SafariBob wrote:

andrewD2 wrote:

that’s not really true. The pixels in a screen have a sub pixel for each color. The camera does not. Hence a 4K display, which is 8mpx is equivalent to a 32mpx photo. Typically, to generate one high quality pixel you need 4, this is why high quality 1080p is supersampled from 4K. This basically implies that a super high quality 4K image needs up to 144mpx.

A 4k wide image at 3:2 isn't 8MP.

I am talking about a 4K image, not “4K wide”

The calculation you are making is the required camera resolution. The camera resolution is cropped for a 16:9 screen. You need to take that into account.

as you say, that’s bizarre. Let’s do the math.

3:2, 4K wide. = 4096 * 4096 * 2/3 = 11.1mpx full colour = 44 camera mpx.

so in order to fill a 4K display with information at each sub pixel you need 44mpx

This is incorrect. And why you are out by a clear factor of 4.
You need ONE pixel per screen "pixel". That pixel is then displayed as subpixels based on the image single pixel's RGB data.
You CAN NOT address each subpixel as you suggest with "more than 4K".

Now I understand why you are so confused.

in a display each “pixel” contains 3 sub pixels (or more) such that each pixel contains full color information.

in a camera, each “pixel” contains just one color. Hence the pixel in a camera is comparable to a sub pixel in a display. For each full color site, there are 2 green, one red and one blue in a camera.

thus an 8k display contains 32 “camera” pixels, which are actually 24 rgb sub pixels.

in order to make the effect of pixels, interpolation, etc negligible, you need to oversample.

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