Image Compression
Image-specific size reduction methods used inside and outside PDFs.
Definition
Can be lossy or lossless depending on codec and settings.
Why it matters
Core quality/size tradeoff for PDF optimization.
Related PDFHQ workflows
Use this concept when optimizing, converting, validating, or troubleshooting document workflows.
Related Knowledge
Techniques used to reduce file size while balancing quality.
HEIC is the common extension for HEIF images encoded with HEVC, especially in Apple-centric capture workflows.
DjVu is a format designed for efficient storage of scanned documents, often with layered text/image approaches.
GIF is an indexed-color raster format known for lightweight animations and simple graphics.
JPEG/JPG is the dominant lossy raster image format for photographs.
WebP is a modern web image format supporting lossy/lossless compression and alpha transparency.
AVIF is an AV1-based image format targeting strong compression efficiency while preserving visual detail.
JP2 (JPEG 2000) is a wavelet-based image format offering high-quality compression options.
HEIF is a high-efficiency image container that can store still images, sequences, and related metadata.
Small preview image representing a document or page.
Converting images into black-and-white pixels for OCR and compression workflows.
JPEG-based compression filter used for many embedded images in PDFs.
Fax-era bi-level image compression commonly used for monochrome document scans.
JPEG 2000-based image compression filter used in some PDF image objects.
Tools to Apply This
Convert images such as JPG and PNG into PDF files.
Convert PDF pages into image files.
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