How can I find the width and height of pixels on a camera display?

Question

I am trying to determine the width and height of the LCD on the camera. I will use the Canon EOS-1DX Mark II as an example.

The display is written as 1,620,000 pixels. This is not intuitive to me as I would like the width and height. I have tried computing in the following way, using the advice of Why does viewfinder spec state 3 times more dots than there are pixels?

I assumed that there are 1,620,000/3=540,000 real pixels and the width:height is in 3:2 ratio (same as the sensor?). By simple arithmetic I arrived at a resolution of 900x600.

Additional Example: The 7D Mark II resolution is listed as 1,036,800 pixels. Using the same basic calculation I arrive at 720x480.

For both examples I arrive and nice round numbers.

Two questions:

1. Are my assumptions correct?

2. Why do manufacturers use this notation for lcd resolution?

Answer 1

This is basic algebra. Assuming that you are correct that the LCD has a 3:2 aspect ratio (this is often true of the sensors in DSLRs, but not necessarily the LCDs - check the specs in your user manual for more info), then you have that 3x * 2x = 6x^2 = 1620000, or x = sqrt(1620000)/6. This means x is about 517, from which you would then get the dimensions - 3x = 1559 and 2x = 1039, so the resolution of the LCD is about 1559x1039.

So, to answer your questions:

1. No, your assumptions were not correct, and
2. Nobody other than the marketing folks know for sure, but I highly suspect it at least involves the notion that bigger numbers seem to be more "impressive", for some not-necessarily-standard definition of "impressive".

Answer 2

After some research I have found the following:

The Canon User Manual does list aspect ratios for their displays (in the Appendix), so there is no need to assume anything there.

On the website https://www.the-digital-picture.com/Reviews/Canon-EOS-1D-X-Mark-II.aspx (in the section 'Back of the Camera') Bryan has the same results on the resolutions that I have.

For #2 I do agree it probably is a marketing thing. One observation I have seen is that Canon is very careful to differentiate between dots and pixels (https://techcrunch.com/2010/07/21/a-quick-psa-on-dots-versus-pixels-in-lcds/)