Learn in the textbookFile Formats for Still Images and Documents
DefinitionPNG is a still-image format that can store even full-color images without degradation using lossless compression (可逆圧縮).
ExplanationIt was created as a web format to replace GIF and can save either with a palette of up to 256 colors or in full color. It supports an alpha channel that gives each pixel its own degree of transparency, so it also works for laying a semi-transparent logo over a background.
AnalogyIt is like packing a high-quality scanned original into a box so carefully that not a single crease forms. It arrives exactly as sent, but the box cannot be made very small.
Memory hookIt stands for Portable Network Graphics, and the word Network shows it was born for use on networks and the web.