Regarding the question.....
When I take a screenshot with Print Screen and examine it, the captured image doesn't match what is on the screen. It loses definition. Is there any way to prevent this and capture/store exactly what is on the screen? Thanks
This is where basic understanding of color management comes into play. I'll keep things real simple.
Windows, like the internet uses the base (universal) sRGB color profile. Think of this as a standard color profile all viewing and imaging devices use (again, keeping things simple). This way all images shown on the net for example look the same from device to device. Of course, device color adjustments will shift colors and tones, but the base info (sRGB color space) is still there. Think of this as putting on a pair of blue glasses and looking at soft yellow flower. That flower will still be soft yellow, but will now have a blue tint seen from your glasses. This is what happens when you adjust your monitor color and why some may say reds look a little less or more vibrant on
their system. The color profile is still sRGB, but their monitors are changing the tones. Again, in keeping things simple. Also understand sRGB is the shallowest (less color tones) of the color gamut - typically sRGB, Adobe 1998, ProPhoto (slightly wider than 1998).
It also doesn't matter the file format - you can assign an sRGB color profile to a tiff file (lossless) or an Adobe 1998 color profile to a Jpeg (lossy) file. Here it's about the color profile, not the file format.
As a photographer, when I process my images, I save them as tiff files (a large file format) saved in ProPhoto color profile because I need the most colors available when I print my work - sRGB, produces less colors and shades than either Adobe 1998 or ProPhoto). However, when I post an image to my photo site, they're a jpeg (smaller file size) copy of the lager tiff file and save with the sRGB color profile so that the colors look consistent across a myriad of viewing devices. They aren't as vibrant as my tiff files shown in Photoshop, but because most browsers just use the standard sRGB color profile, that's what I use when posting images to the net.
It also helps to understand a color managed system is more or less a closed environment. That you'd need to be working in a color managed environment (example Photoshop) to effectively use the wider colored profiles - Adobe 1998, ProPhoto. Again, keeping things simple; again, reminding Windows use the base sRGB color profile in its environment.
With that out the way, some snip/screen capture tools (example Windows Snip tool, Snagit) don't use color management (assign a color profile) when you take a screen capture there, and thus why colors looks dull and lifeless. You can when using a "color managed" photo editing app like Photoshop....
When you attempt to open the image in Photoshop you will be notified the image taken, in the case with either the snipping tool or Snagit, has no color profile, and you're given the opportunity to assign one. Here are two snips taken - one with the Windows Snipping tool, one with Snagit. Both have
no color profile embedded....
Here I could use the working profile I've setup for Photoshop, or I can use the dropdown box to choose the sRGB color space.
Left is an image shot with my cell phone with the sRGB profile assigned. Right is that same image screen captured (and without a profile assigned)....
Notice how dull (red and blue colors) the right is compared to the left (which has the sRGB color profile included).
I can't speak for all screen capture/snipping tools, but I know at least Windows Snip, and Snagit doesn't assign color profiles to their snips, and so if color is of importance to you, you'll need an image editing tool that allow one to be assigned.
As you can see, even in trying to keep thing simple can turn long winded where color management concerned. Also note T.V. screens are a different breed where color management comes in so that's another story not applicable here.
Hope this helps.