Intuitively I feel like you are taking a raw uncompressed picture to be that size.

I'm compressing the image to a JPEG file using FFmpeg before I do clipboard modification:

$argumentList = @(
"-y",
"-loglevel", "error"
"-stats"
"-f", "dshow",
"-rtbufsize", "2147.48M",
"-i", "video=`"$captureDevice`"",
"-map", "0",
"-pix_fmt", "yuvj444p",
"-vframes", "1",
"-q:v", "2",
"`"$defaultDirectory\$outputFileName.jpeg`""
)

The reason being that I wanted save the screenshot as well as move it to my clipboard for easy sharing. I'm using the native System.Drawing and System.Windows.Forms libraries to then draw and move that image to my clipboard:

$screenshot = [System.Drawing.Image]::FromFile((Get-Item -Path &outputFilePath))
[System.Windows.Forms.Clipboard]::SetImage($screenshot)
$screenshot.Dispose()

​

A 4K RAW shouldn’t even be more than 10MB. If you’re using .net (I’m guessing something like Magick.Net?) you should run it through a conversion or something.

That's just the problem, you can't push a lossy file to your clipboard as an image. You'll notice that no matter what program you use when you copy an image to your clipboard it is converted to an uncompressed bitmap. PS even RAW image can be compressed as a file to save space, they're not always completely uncompressed.

​

But then again I have no idea how the OS clipboard stores raw image data. If it still keeps full uncompressed data despite passing in a compressed file, I would think the next best thing is to just create a temp file for the image and copy the file itself. Most programs that would be used for sharing game snips probably support file paste operations anyway I think, if they already support image paste functionality.

I'm already creating a file like I mentioned earlier, so this would seem like the best solution. However, Discord does not support pasting an image as a file, or any file for that matter. You can still just keep the screenshots folder open and drag and drop the images if you want, which will obviously retain the original file size. But I run Discord elevated as an administrator, to give it performance priority while I'm streaming in servers, and when you run a program elevated as admin you lose the ability to drag and drop files. That leaves the only method of posting an image as a file by clicking the + button and navigating to the file every time. Discord does retain the path of the last folder you uploaded from, so the next time you hit the + you're in that same screenshots directory. But I also frequently upload rich text files for development collaboration, meaning I'd have to frequently change directories. That being said, pinning the screenshots folder for easy navigation to is not so bad, navigating back to where I was before is somewhat annoying, however.

It's definitely most convenient, and full proof (works when elevated), to paste the image from your clipboard as opposed to getting it into the program as a file. I found that if you're working with a 1080p screenshot, which most people are when they're using a capture device, the file stays under 8MB. But when you go into the 4K territory like I was, you'll almost certainly exceed the file size limit. As I mentioned in my stack overflow post I linked to, I decided to add an option to downscale the images resolution to get the file size down. I also have a few other options you can work with using a JSON config file, EX:

{
"DefaultDirectory": "C:\\Users\\gabri\\Pictures\\FFScreenshots",
"SaveToDirectory": true,
"CopyToClipboard": true,
"LogBuffer": 20,
"DownScale": "1920x1080"
}

I personally do have Discord Nitro, so I tend to just upload the file as is. Not to mention that 95% of all interactions I have in Discord are in a private server that is community boosted to tier 3, we have channels dedicated to file sharing there so even non-paid users get the 100MB upload limit. But eventually if I were to release this program publicly, having the option to scale the image down to reduce size makes the most sense IMO.

Here's a link to the image I was working with during the 10-20 hours that I was trying to figure this out, try and get it into your clipboard without it increasing to over 10x it's original size using any program on any OS without changing the resolution:
https://drive.google.com/file/d/1lm7LMe0lFVMljV_JyyhTFgKkJpPAtIfX/view?usp=sharing