BMP dates to 1985. TIFF dates to 1986. ICO dates to 1985. These formats predate the World Wide Web by nearly a decade. They seem like candidates for a museum — until you encounter the specific workflows that still require them.

BMP provides raw pixel data with zero computational overhead — essential in embedded systems and real-time image processing. TIFF's tag-based architecture supports color spaces, bit depths, and multi-page structures that no web format can match — making it irreplaceable in print, medical imaging, and GIS. ICO's multi-resolution container remains required for Windows favicons.

This guide covers when these formats are genuinely the right tool, when they're not, and how to convert between them and modern formats. If you're here because someone sent you a BMP or TIFF and you just need a usable file: convert BMP to PNG or convert TIFF to JPG.

BMP: The Uncompressed Standard

BMP (Bitmap Image File) is Windows' native image format. It stores pixel data with minimal or no compression, making files enormous but trivially fast to parse.

Technical Architecture

A BMP file consists of a 14-byte file header, a variable-size info header (typically 40 bytes for BITMAPINFOHEADER), an optional color palette, and raw pixel data. The pixel data is stored bottom-to-top (the last row of pixels comes first), padded to 4-byte row boundaries.

File size is completely predictable:

  • 1920 x 1080 at 24-bit: exactly 5,760,054 bytes (5.5 MB)
  • 3840 x 2160 at 24-bit: exactly 24,883,254 bytes (23.7 MB)
  • 4000 x 3000 at 24-bit: exactly 36,000,054 bytes (34.3 MB)

Formula: width * height * (bits_per_pixel / 8) + header_size + row_padding. No surprises.

Compression options: BMP technically supports RLE (Run-Length Encoding) for 4-bit and 8-bit modes, but RLE BMPs are rare in practice. There's also a BI_JPEG and BI_PNG mode where the BMP wraps JPEG or PNG data — equally rare and poorly supported.

When BMP Is Actually the Right Choice

Embedded systems and microcontrollers: Devices with limited processing power but sufficient storage benefit from BMP's zero-decompression requirement. Reading a BMP is a memory copy; decoding PNG requires implementing DEFLATE. For firmware splash screens, industrial HMI displays, and boot logos, BMP's simplicity is an advantage.

Image processing pipelines: When you're doing pixel-level operations (edge detection, color analysis, compositing), working with raw pixel arrays is natural. BMP is essentially a raw pixel array with a header. Many image processing libraries read BMP as their simplest input format.

Windows clipboard: The Windows clipboard's DIB (Device-Independent Bitmap) format is BMP-compatible. Copy-paste operations between Windows applications often use BMP internally.

Diagnostic/debugging: When you need to inspect exact pixel values without any compression interference, BMP guarantees what you saved is exactly what you'll read back.

For everything else — web, email, documents, sharing — convert to PNG (lossless) or JPEG (photos): BMP to PNG | BMP to JPG | BMP to WebP.

TIFF: The Print Industry Workhorse

TIFF (Tagged Image File Format) is the most flexible raster image format in existence. Its tag-based architecture can represent almost any image data type — and that flexibility is both its strength and its weakness.

Tag-Based Architecture

TIFF files are organized around Image File Directories (IFDs), each containing tags that describe the image. Standard tags define dimensions, color space, bit depth, compression, resolution, and more. Private tags allow vendors to embed custom data — which is why Adobe Photoshop TIFF files contain tags that other software may not understand.

Compression options:

  • None: Raw pixel data. Maximum compatibility, maximum size.
  • LZW: Lossless dictionary compression. Good balance of size and compatibility. Most software handles LZW TIFF.
  • ZIP (DEFLATE): Same algorithm as PNG. Slightly better compression than LZW. Good software support.
  • JPEG: Lossy compression inside a TIFF container. Rarely used — if you want JPEG compression, just use JPEG.
  • PackBits: Simple RLE. Fast but minimal compression. Used in some fax and scanner workflows.

Byte order: TIFF files can be big-endian ("MM" header, Motorola byte order) or little-endian ("II" header, Intel byte order). This is specified in the first two bytes of the file. Most modern software handles both transparently.

Color Spaces and Bit Depths

This is where TIFF's flexibility shines:

  • RGB: 8-bit (24-bit total) or 16-bit (48-bit total) per channel
  • CMYK: 8 or 16 bits per channel. Critical for print — CMYK color space maps directly to cyan, magenta, yellow, and black ink. No web format supports CMYK.
  • Lab color: Device-independent color space used in color science and professional color management
  • Grayscale: 1 to 16 bits per pixel
  • Floating-point: 32-bit float per channel for HDR and scientific imaging

The 16-bit mode (65,536 values per channel vs 8-bit's 256) provides maximum editing latitude. Professional photographers shoot RAW, develop in Lightroom/Capture One, and export to 16-bit TIFF for final retouching in Photoshop. The extra bit depth prevents banding when making extreme tonal adjustments.

Multi-Page TIFF

TIFF supports multiple images in a single file through multiple IFDs. This is heavily used in document workflows: scanning a 50-page document produces a single multi-page TIFF. Fax systems use multi-page TIFF (G3/G4 compressed) as their standard format.

Multi-page TIFF is also used in scientific imaging (microscopy stacks, time-series data) and GIS (geo-referenced image layers). No other common image format handles multi-page this well — PDF can, but PDF is a document format, not an image format.

When to Use TIFF

Print production: Print shops expect TIFF or PDF. TIFF supports CMYK natively, handles the resolution metadata printers need (300 DPI at exact dimensions), and preserves 16-bit color depth for professional-grade output.

Archival: TIFF with LZW or no compression is the archival standard for libraries, museums, and government agencies. It's an ISO standard (ISO 12639 for TIFF/IT), widely supported, and stores maximum quality without patent encumbrances.

Medical imaging: DICOM files often contain TIFF-compatible image data. 16-bit grayscale TIFF preserves the full dynamic range of X-rays, CT scans, and MRI images.

GIS and satellite imagery: GeoTIFF extends TIFF with geographic coordinate system metadata. It's the standard format for satellite imagery, elevation models, and geographic data layers.

For web use, always convert: TIFF to JPG | TIFF to PNG | TIFF to WebP.

ICO: The Favicon Container

ICO is a multi-resolution image container created for Windows icons. Each ICO file contains multiple images at different sizes (16x16, 32x32, 48x48, 256x256), and the operating system or browser picks the most appropriate size for the context.

Structure and Usage

An ICO file has a directory listing each contained image's dimensions, color depth, and offset within the file. Each image is stored as either BMP (traditional, up to 32-bit RGBA) or PNG (modern, better compression). A typical favicon.ico with three sizes (16x16, 32x32, 48x48) as PNG is 3-10KB.

For web favicons in 2026, you need:

  • /favicon.ico at the site root — 32x32 is the minimum, include 16x16 and 48x48 for maximum coverage. Browsers still request this path by default.
  • <link rel="icon" type="image/png" href="/icon-192.png"> — modern browsers prefer this for tab icons and bookmark icons.
  • Optionally, <link rel="icon" type="image/svg+xml" href="/icon.svg"> — SVG favicons scale perfectly and support dark mode via prefers-color-scheme.

Create ICO files from PNG: PNG to ICO | SVG to ICO. Extract from ICO: ICO to PNG.

Other Legacy Formats Worth Knowing

PCX: ZSoft's paintbrush format, popular in DOS-era games and graphics. Encountered occasionally in legacy software archives. Convert to PNG for modern use.

TGA (Targa): Truevision's format, still used in game development and 3D rendering pipelines (Unreal Engine, Unity). Supports alpha, RLE compression. Simple to parse, which is why game engines keep it around.

PPM/PGM/PBM (Netpbm): Simple ASCII or binary image formats used in Unix image processing pipelines. Essentially plain-text pixel data. Useful as intermediate formats in command-line processing chains (ImageMagick reads/writes them natively).

EPS (Encapsulated PostScript): Vector format from the PostScript printing era. Still encountered in legacy print workflows and clip art libraries. Most modern tools can import EPS but prefer SVG or PDF for new work. Convert EPS to PNG | EPS to SVG.

When Legacy Is the Right Choice

The decision tree is simple:

  • Need raw pixel data with zero decode overhead? → BMP
  • Need CMYK for print production? → TIFF
  • Need 16-bit color for professional editing? → TIFF
  • Need multi-page scanned documents? → TIFF
  • Need geographic coordinate embedding? → GeoTIFF
  • Need Windows favicon? → ICO
  • Everything else? → PNG, WebP, AVIF, or JPEG

Legacy formats aren't obsolete — they're specialized. They solve problems that modern web-optimized formats weren't designed for. The mistake is using them outside their niche: serving TIFF on the web, emailing BMP files, or using ICO for anything except favicons.

BMP, TIFF, and ICO exist for reasons that modern web formats don't address. BMP provides raw pixel access. TIFF handles professional color workflows and multi-page documents. ICO solves the multi-resolution favicon problem. Using them for their intended purpose is smart; using them for web delivery is not.

When you encounter these formats and need something more universal, ChangeThisFile handles the conversion: BMP to PNG, TIFF to JPG, TIFF to WebP, ICO to PNG, and PNG to ICO for favicon creation. Free, no signup.