Image Format Technical Specifications
Each image format has unique technical capabilities that make it suitable for specific applications. Understanding these functions helps in selecting the right format for your needs.
JPEG/JPG Technical Functions
Compression Type: Lossy (Discrete Cosine Transform)
Color Depth: 24-bit (16.7 million colors)
Transparency: Not supported
Animation: Not supported
Metadata: EXIF, IPTC, XMP support
Best Compression Quality: 80-90% for optimal quality/size balance
PNG Technical Functions
Compression Type: Lossless (DEFLATE algorithm)
Color Depth: Up to 48-bit color, 16-bit grayscale
Transparency: Alpha channel support (variable transparency)
Animation: APNG extension supports animation
Metadata: Limited support for text metadata
Interlacing: Adam7 interlacing for progressive loading
WebP Technical Functions
Compression Type: Both lossy and lossless options
Color Depth: 24-bit and 32-bit with alpha
Transparency: 8-bit alpha channel (even for lossy)
Animation: Supported with keyframe compression
Advanced Features: Predictive coding, VP8 video format
Efficiency: Typically 25-35% smaller than equivalent JPEG/PNG
GIF Technical Functions
Compression Type: Lossless (LZW compression)
Color Depth: 8-bit (256 colors maximum)
Transparency: 1-bit transparency (on/off)
Animation: Native support with frame delay control
Palette: Global and local color tables
Interlacing: Supported for progressive loading
BMP Technical Functions
Compression Type: Typically uncompressed (optional RLE compression)
Color Depth: 1-bit to 32-bit color
Transparency: Alpha channel support in newer versions
Animation: Not supported
Structure: Bitmap file header, DIB header, color table, pixel array
Platform: Primarily Windows format
PDF Technical Functions
Content Type: Mixed content (text, vector, raster images)
Compression: Multiple options (JPEG, ZIP, LZW, CCITT)
Vector Support: Native vector graphics support
Text Capabilities: Embedded fonts, text search and selection
Interactive Features: Forms, annotations, digital signatures
Security: Encryption, password protection, permission controls
Frequently Asked Questions
Lossless compression uses algorithms that preserve all original data exactly. When decompressed, the output is identical to the original input. Examples include PNG's DEFLATE algorithm and GIF's LZW compression.
JPEG uses Discrete Cosine Transform (DCT) to convert image data into frequency components, then quantizes these components, reducing less important visual information. This process is lossy but optimized for human visual perception.
Alpha channel transparency allows for variable transparency levels (0-100%) for each pixel. This creates smooth transitions between opaque and transparent areas, unlike 1-bit transparency which only supports fully opaque or fully transparent pixels.
WebP uses predictive coding that analyzes blocks of pixels to predict their values, then only stores the difference from the prediction. This is more efficient than JPEG's DCT method, especially for areas with similar colors.
Color depth refers to the number of bits used to represent each pixel's color. Higher color depth allows more colors: 8-bit = 256 colors, 24-bit = 16.7 million colors, 48-bit = 281 trillion colors.