Free webp to jpg
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Image MIME Reference
DDS

DirectDraw Surface

image/vnd.ms-dds
VS

Windows Icon (Legacy MIME)

image/x-icon
ICO

A complete technical comparison of DirectDraw Surface and Windows Icon (Legacy MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

ICO wins on browser support

Feature Support

Feature DDS ICO
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
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 →
Windows Icon (Legacy MIME)
image/x-icon
Extension
.ico
Container ICO Directory Structure
Compression Uncompressed (DIB/BMP) / Deflate (Embedded PNG)
Algorithm
NoneDeflate (via PNG)
Color Depth 1-bit, 4-bit, 8-bit, 24-bit (True Color), 32-bit (RGBA)
Developed by Microsoft Corporation
Released 1985
Magic Bytes
00 00 01 00
Full ICO reference →

Browser Support Comparison

Browser DDS ICO
Chrome Chrome
✕
✓ 1
Firefox Firefox
✕
✓ 1
Safari Safari
✕
✓ 1
Edge Edge
✕
✓ 12
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
ICO

ICO Strengths

  • Universally supported by every web browser in existence for website favicons
  • Packs multiple resolutions into a single file, eliminating the need to serve different files for the taskbar vs. the desktop
  • Modern support for embedded PNGs (since Windows Vista) allows for excellent 32-bit transparency (alpha channels) and drastically reduced file sizes
Limitations
  • Internal file structure is convoluted due to decades of legacy cruft, such as the requirement for BMP data to lack a standard file header but double the height property for an archaic XOR/AND mask
  • Larger file size compared to a single optimized PNG or SVG, as it literally stores the same image multiple times at different scales
  • The MIME type landscape is highly fragmented (x-icon vs. vnd.microsoft.icon), causing occasional caching or strict-MIME validation errors on restrictive servers

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)
ICO
Use ICO when…
  • Website Favicons (favicon.ico)
  • Windows Application Executable Icons (.exe)
  • Desktop Shortcut Icons

More comparisons

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