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Category Image Converters

Drop BMP file here or click to browse

Supports 24-bit and 32-bit uncompressed BMP

Compression Method

LZW (Best compression) PackBits (Fast encoding) None (Maximum compatibility)

Output Resolution (DPI)

Auto-detect from BMP

Output Filename

.tiff

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About

BMP files lack compression and metadata capabilities required for archival and print workflows. Converting to TIFF provides lossless compression options (LZW reduces file size by 40 - 60% without quality loss), embedded ICC profile support, and multi-page document compatibility. Incorrect conversion strips essential IFD tags - corrupting files that appear valid but fail in professional RIP software. This tool implements the TIFF 6.0 specification with proper byte alignment, tag ordering (ascending by code), and rational number encoding for resolution fields (XResolution, YResolution stored as two 32-bit unsigned integers). Processing occurs entirely client-side; your images never leave the browser.

Formulas

BMP row padding ensures each scanline aligns to a 4-byte boundary. The padding calculation:

padding = (4 − (width × bytesPerPixel) mod 4) mod 4

where width = image width in pixels, bytesPerPixel = 3 for 24-bit or 4 for 32-bit BMP.

TIFF RATIONAL fields encode resolution as a fraction:

DPI = numeratordenominator

LZW compression uses variable-width codes starting at 9 bits, expanding to 12 bits maximum. Clear code = 256, EOI code = 257. Dictionary builds dynamically during encoding.

Reference Data

TIFF Tag	Code	Type	Description
ImageWidth	256	SHORT/LONG	Pixel width of image
ImageLength	257	SHORT/LONG	Pixel height of image
BitsPerSample	258	SHORT	Bits per color channel (typically 8)
Compression	259	SHORT	1=None, 5=LZW, 32773=PackBits
PhotometricInterpretation	262	SHORT	2=RGB, 1=BlackIsZero
StripOffsets	273	LONG	Byte offset to image data strips
SamplesPerPixel	277	SHORT	Channels per pixel (3=RGB, 4=RGBA)
RowsPerStrip	278	SHORT/LONG	Rows in each data strip
StripByteCounts	279	LONG	Bytes in each compressed strip
XResolution	282	RATIONAL	Horizontal DPI (numerator/denominator)
YResolution	283	RATIONAL	Vertical DPI (numerator/denominator)
ResolutionUnit	296	SHORT	1=None, 2=Inch, 3=Centimeter
Software	305	ASCII	Creating software identifier
DateTime	306	ASCII	Creation timestamp (YYYY:MM:DD HH:MM:SS)
ExtraSamples	338	SHORT	Alpha channel type (1=Associated, 2=Unassociated)
Predictor	317	SHORT	Horizontal differencing for LZW (2)

Frequently Asked Questions

Yes. The conversion is mathematically lossless. Each pixel's RGB values transfer exactly from BMP to TIFF. LZW and PackBits are lossless compression algorithms - they reduce file size without discarding data. Uncompressed TIFF produces byte-identical pixel data to the source BMP.

LZW achieves better compression ratios (typically 40-60% size reduction) for photographs and complex images. PackBits performs better on images with large uniform areas (diagrams, screenshots) and has faster encoding. Uncompressed is safest for maximum compatibility with legacy software but produces larger files.

32-bit BMPs contain an alpha channel (transparency). The converter preserves this as a 4-channel TIFF with ExtraSamples tag. If your image has no meaningful transparency, convert the source to 24-bit BMP first, or the extra channel adds 33% overhead before compression.

This tool supports Windows BMP v3 (BITMAPINFOHEADER) in 24-bit and 32-bit uncompressed formats - covering over 95% of BMP files in circulation. RLE-compressed BMPs, OS/2 formats, and 16-bit color depths are not supported and will display a validation error.

BMP stores resolution in pixels per meter. The converter extracts this value and converts to DPI (pixels per inch) for TIFF output using the factor 0.0254 meters per inch. If the BMP lacks resolution metadata (value = 0), the tool defaults to 72 DPI - standard screen resolution.