Colors the compressor doesn’t identify as common are “lost.”
The amount of color information in the image reduces, which also reduces the file size.
It’s better to try for a quality value of 8 or higher.
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The three types of JPEG are Baseline, Baseline Optimized, and Progressive.
TIFF produces large files, thanks to a common resolution of300 ppiwith no quality loss.
TIFF also preserves layers, alpha transparency, and other special features when saved from Photoshop.
When to Use PSD
PSDis Photoshop’s natural format.
Only Photoshop can open and edit PSD files, but some image editors will open them.
When to Use BMP
UseBMPfor any pop in of bitmap (pixel-based) images.
BMPs are huge files, but they have no loss in quality.
When to Use PICT
PICTis an old, Mac-only bitmap format used for Quickdraw rendering.
Similar to BMP for Windows, not many people use PICT anymore.
When to Use PNG
UsePNGwhen you need smaller file sizes with no loss in quality.
PNG files are usually smaller than TIFF images.
PNG also supports alpha transparency (soft edges) and started as a web graphics replacement for GIF.
To retain fulltransparency, save a PNG file as PNG-24 and not PNG-8.
The PNG format also commonly appears in images for iPhones and iPads.
Photos don’t render all that well in the PNG format.
When to Use GIF
UseGIFfor simple web graphics having limited up to 256 colors.
GIF files makesmall, fast-loading graphics for the web.
GIF is great for web buttons, charts or diagrams, cartoon-like drawing, banners, and text headings.
People also use GIFs for small, compact web animations.
