Colors don’t match on sample using 2 computers

[topheavyproductions]

I am viewing a Photoshop training video that has sample files to use. The video gives instructions for both Windows PC and Mac due to different key combinations for each system (ctrl vs cmd). I have both types of systems so I am doing the training simultaneously on each. These are the questions.

1) When I open the same sample file on each computer, the color readings different, i.e. the RBG colors on the PC aren't the same on the Mac for the same pic. This concerns me because if I work between 2 computers and possibly an iPad also how can I be sure of the image quality if the colors change for each system being used?

2) a second question which isn't as crucial. Both computers are laptops. The Windows in 15" and the MacBook Pro 16". When I open the same sample file on each, it opens on the PC at 50%, which just about matches the training video, but opens on the MacBook at 100% yet they look the same size on the monitors. Why would 50% on one equate to 100% on the other. Thus when I enlarge the image to fill the screen, the PC image is still below 100% while the MacBook image is now 200%. Why all these difference for the identical sample file?

[D Fosse]

To see correct colors you need to observe basic color management procedure.

• the file needs to have an embedded icc color profile (sRGB, Adobe RGB, ProPhoto, DCI-P3). This defines the RGB numbers as actual colors. Without it it's just empty and meaningless numbers.
• you need to have an accurate and valid monitor profile on your system. The way to get that is to use a calibrator, which measures your display and writes a profile describing its behavior in detail. This profile is also written to icc specifications.
• you need to use applications that support color management, i.e. reads both these profiles and converts correctly from one to the other. Photoshop, Lightroom, Illustrator etc are all color managed, but many consumer-oriented image viewers are not. They can not be trusted.

If you follow these standard procedures, it doesn't matter whether you are on a Mac or a Windows machine. They will both handle the file correctly, and therefore identically.

[Per Berntsen]

Why would 50% on one equate to 100% on the other. Thus when I enlarge the image to fill the screen, the PC image is still below 100% while the MacBook image is now 200%. Why all these difference for the identical sample file?

100% view means that one image pixel is represented by one screen pixel.

Your MacBook probably has a much higher screen resolution than your PC. 

I don't know what the screen resolutions are, but if the MacBook has 3840 pixels on the long side, and the PC has 1920, the MacBook will display images much smaller (roughly half the size) at the same magnification, because the pixels are much smaller.