Free webp to jpg
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Image MIME Reference
DDS

DirectDraw Surface

image/vnd.ms-dds
VS

Portable Graymap

image/x-portable-graymap
PGM

A complete technical comparison of DirectDraw Surface and Portable Graymap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature DDS PGM
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
DirectDraw Surface
image/vnd.ms-dds
Extension
.dds
Container DirectDraw Surface
Compression Block Compression (BC1-BC7) / DXTC / S3TC / Uncompressed (RGBA, Floating-Point)
Algorithm
DXT1-DXT5BC1-BC7ASTC / ETC2 (Extended)
Color Depth 8-bit, 16-bit, 24-bit, 32-bit (RGBA), 16-bit/32-bit Floating Point (HDR)
Developed by Microsoft Corporation
Released 1999
Magic Bytes
44 44 53 20
Full DDS reference →
Portable Graymap
image/x-portable-graymap
Extension
.pgm
Container Netpbm
Compression Uncompressed
Algorithm
None
Color Depth 8-bit (Grayscale), 16-bit (Grayscale)
Developed by Jef Poskanzer (Netpbm Project)
Released 1988
Magic Bytes
50 32 (ASCII) or 50 35 (Binary)
Full PGM reference →

Browser Support Comparison

Browser DDS PGM
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
DDS

DDS Strengths

  • Massively reduces VRAM footprint and memory bandwidth usage because the GPU decodes the block compression in hardware
  • Encapsulates complex texture arrays, volume textures, cubemaps, and entire mipmap chains within a single, highly structured file
  • Supports high-dynamic-range (HDR) floating-point data for modern physically based rendering (PBR)
Limitations
  • Block compression algorithms (like DXT) are lossy and can introduce ugly blocky artifacts, especially in smooth gradients or normal maps if not tuned properly
  • Files are generally larger on the physical hard drive than highly compressed formats like PNG or WebP
  • Zero support in web browsers or standard consumer image viewers
PGM

PGM Strengths

  • Extremely simple format allows custom parsers to be written from scratch in minimal time
  • Supports 16-bit precision, making it highly valuable for scientific, medical, and height-map data where 8-bit precision is insufficient
  • ASCII encoding ('P2') allows manual editing and visual inspection of pixel values directly within a text editor
Limitations
  • Strictly limited to grayscale; cannot display color
  • Lack of compression results in massive file sizes, making it entirely impractical for web delivery or consumer storage
  • Does not support alpha transparency or modern metadata structures

When to choose which format

DDS
Use DDS when…
  • Real-Time 3D Game Textures
  • DirectX and Vulkan Rendering Pipelines
  • Skyboxes and Environment Cubemaps
  • Volume Textures (3D Textures)
PGM
Use PGM when…
  • Computer Vision and Machine Learning Pre-processing
  • Scientific and Medical Image Processing
  • Unix/Linux Command-Line Image Pipelines

More comparisons

DDS vs ACES → PGM vs ACES → DDS vs APNG → PGM vs APNG → DDS vs AVCI → PGM vs AVCI → DDS vs AVCS → PGM vs AVCS → DDS vs AVIF → PGM vs AVIF → All comparisons →
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