Image terms, explained simply
Short, clear answers to common questions about image formats, compression, and quality. Each one links to a free tool that does the job.
What is a WebP file?
WebP is an image format developed by Google that compresses photos and graphics smaller than JPG or PNG at the same quality. A WebP file uses the .webp extension, supports both lossy and lossless compression, and can store transparency and animation. Every major browser released since 2020 displays WebP natively.
ReadWhat is a transparent PNG?
A transparent PNG is a PNG image with no background, so whatever sits behind it shows through. PNG stores an alpha channel that records how opaque each pixel is, which lets a logo or cutout sit cleanly on any color. JPG cannot hold transparency, which is why cutouts are saved as PNG.
ReadWhat is an alpha channel?
An alpha channel is the part of an image that stores transparency. Alongside the red, green, and blue color channels, the alpha channel records how opaque each pixel is, from fully solid to fully see-through. Formats like PNG and WebP support an alpha channel; JPG does not.
ReadLossy vs lossless compression
Lossy compression makes a file smaller by permanently discarding some image detail, while lossless compression shrinks the file without throwing anything away. JPG and default WebP are lossy; PNG and lossless WebP keep every pixel. Lossy produces smaller files, and lossless keeps perfect quality.
ReadWhat is DPI?
DPI (dots per inch) measures how many dots a printer places in one inch of paper. It affects printing only, not how an image looks on a screen, where the pixel dimensions are what matter. A photo at 300 DPI prints sharply, while the same file shown online is judged by its pixel width and height.
ReadWhat is an SVG file?
SVG (Scalable Vector Graphics) is an image format that describes shapes with math instead of pixels, so it stays sharp at any size. SVG files use the .svg extension, are written in XML text, and are ideal for logos, icons, and line art. Photos are a poor fit because they are made of pixels, not shapes.
ReadWhat is aspect ratio?
Aspect ratio is the relationship between an image's width and height, written as two numbers like 16:9 or 1:1. It describes the shape of the image, not its size, so a 1:1 square looks the same whether it is 500 or 5000 pixels wide. Matching the right aspect ratio stops platforms from cropping your image.
ReadWhat is image resolution?
Image resolution is the number of pixels an image contains, written as width by height, such as 1920 by 1080. More pixels mean more detail and a sharper picture at larger sizes. Resolution is separate from file size and from DPI, which only matters for printing.
ReadWhat is a GIF?
A GIF (Graphics Interchange Format) is an image format that can hold a short, looping animation in a single file. GIFs use the .gif extension and a palette of up to 256 colors, which keeps them simple but makes them large for detailed motion. For longer or higher-quality animation, MP4 video is far smaller.
ReadWhat is EXIF data?
EXIF data is hidden information a camera or phone stores inside a photo, including the date, camera settings, and often the GPS location where it was taken. It travels with the file when you share it. Removing EXIF data protects your privacy by stripping details like where a photo was shot.
ReadPNG vs JPG: which should you use?
PNG and JPG are the two most common image formats. PNG uses lossless compression and supports transparency, which suits logos, screenshots, and graphics with text. JPG uses lossy compression for much smaller photo files but cannot store transparency. Use PNG for sharp graphics and JPG for photographs.
ReadWhat is a favicon?
A favicon is the small icon a browser shows in the tab, bookmarks, and history next to a page's title. It is usually a square image, commonly 16x16, 32x32, or 512x512 pixels, saved as an .ico or .png file. A clear favicon helps people find your tab among many that are open.
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