The minimum is actually about 2 MB, but those don't exist anymore so you can pretty much look for any graphics card.
If the image is 800 pixels by 600 pixels at 240 pixels per inch, then the image size is (800 / 240) by (600 / 240) or 31/3 by 21/2 inches.
A GIF image can hold up to 256 different colors per image.
16,772,216 Colors
65,536 colors
If you've saved an image as a JPEG, tough luck. It's gone for good, unless you have all the colors of the original image(I'm assuming that you have a computer-generated image that you save as a JPEG) saved somewhere safe, like in your custom colors section, and you are willing to take the time to replace all the colors.
A greyscale image is a graphic image which is rendered completely in black and white and shades of grey, no other colors.
what will a browser do if it cannot exactly match the original colors selected for an image
Open image. At top of screen, click IMAGE>MODE>RGB.
First check resolution from Image - Image Size, then convert to CMYK colors from Image - Mode - CMYK
The colors of the Argentina flag are blue and white. See the related link for an image.
Image > Adjustments > Match Color
Contrasting colors. Light colors stack onto darker shades.