About

A bitmap image at its most fundamental level is a grid of binary pixel states. This tool performs direct conversion from raw binary values (0 and 1) into a valid BMP file conforming to the Windows BITMAPINFOHEADER specification. Each 1 maps to a foreground pixel and each 0 maps to a background pixel. The output is a genuine 24-bit uncompressed BMP file constructed byte-by-byte in the browser, not a screenshot or canvas export. Incorrect row padding or inverted scanline order will produce a corrupted file that image viewers reject. This tool handles the padding calculation (rows must align to 4-byte boundaries) and bottom-up row ordering automatically.

Use cases include QR code prototyping, sprite design, font glyph creation, and visualizing binary data streams from embedded systems or memory dumps. The tool approximates ideal conversion assuming a rectangular grid. If your input rows have unequal lengths, shorter rows are right-padded with 0. Maximum supported resolution is 1024×1024 pixels. Pro tip: paste raw binary output from microcontroller UART logs directly. The parser strips common delimiters (commas, spaces, pipes) automatically.

Formulas

The BMP file size is computed from the image dimensions and the 24-bit pixel format. Each pixel occupies 3 bytes (BGR). Each row must be padded to a 4-byte boundary.

padding = (4 − (W × 3) mod 4) mod 4

rowSize = W × 3 + padding

pixelDataSize = rowSize × H

fileSize = 54 + pixelDataSize

Where W = image width in pixels, H = image height in pixels. The constant 54 is the combined header size (14-byte file header + 40-byte DIB header). Scanlines are stored bottom-to-top: the first row in the pixel data block corresponds to the bottom row of the displayed image. Each pixel is stored in BGR order (blue byte first, then green, then red), not RGB.

Reference Data

BMP Field	Offset (bytes)	Size (bytes)	Value / Description
Signature	0	2	0x42 0x4D ("BM")
File Size	2	4	Total bytes: header + pixel data
Reserved	6	4	0x00000000
Pixel Data Offset	10	4	54 (14 + 40)
DIB Header Size	14	4	40 (BITMAPINFOHEADER)
Image Width	18	4	Pixels (signed 32-bit)
Image Height	22	4	Pixels (positive = bottom-up)
Color Planes	26	2	1
Bits Per Pixel	28	2	24 (RGB, no alpha)
Compression	30	4	0 (BI_RGB, uncompressed)
Image Data Size	34	4	rows × (width × 3 + padding)
H Resolution	38	4	2835 px/m (~72 DPI)
V Resolution	42	4	2835 px/m (~72 DPI)
Colors Used	46	4	0 (all colors)
Important Colors	50	4	0
Row Padding	-	0-3	(4 − (w × 3) mod 4) mod 4
Pixel Order	-	-	BGR (Blue, Green, Red) per pixel
Scanline Order	-	-	Bottom row first (inverted)
Max Width (this tool)	-	-	1024 pixels
Max Height (this tool)	-	-	1024 pixels
Typical 8×8 File Size	-	-	250 bytes
Typical 32×32 File Size	-	-	3,126 bytes
Typical 256×256 File Size	-	-	196,662 bytes

Frequently Asked Questions

The BMP specification inherits alignment requirements from Windows GDI (Graphics Device Interface). Memory-aligned rows enable faster blitting operations on x86 architectures where DWORD (4-byte) aligned reads are significantly faster. The padding bytes are always 0x00. For a width of 5 pixels at 24-bit depth, each row uses 15 bytes of pixel data, padded to 16 bytes (1 byte padding).

The converter determines the maximum row length across all input rows and uses that as the image width W. Shorter rows are right-padded with 0 values (background color). This means missing bits on the right side of shorter rows appear as background pixels. To avoid unintended results, ensure all rows contain the same number of binary digits.

Yes. The parser accepts multiple delimiter formats: spaces, commas, semicolons, pipes, and newlines. A typical UART dump like 1,0,1,1,0,0,1,0 per line is parsed correctly. Strip any non-binary preamble (timestamps, addresses) before pasting. The tool ignores all characters except 0, 1, and delimiter characters.

This is a legacy of the Windows GDI and Intel's little-endian architecture. When a 32-bit color value 0x00RRGGBB is stored in little-endian memory, the bytes appear as BB GG RR 00. The 24-bit BMP format simply drops the alpha byte, leaving BGR order. Every BMP reader expects this convention.

The tool caps input at 1024×1024 pixels (1,048,576 binary values). At 24-bit depth with padding, this produces a file up to approximately 3.1 MB. The BMP encoding runs synchronously in the browser and completes in under 200 ms for grids up to this size on modern hardware. For larger images, consider a server-side solution.

Yes. The tool provides color pickers for both the 1-bit (foreground) and 0-bit (background) colors. These hex colors are converted to BGR byte triplets during BMP encoding. The default is black foreground (#000000) on white background (#FFFFFF).

The first row you type in the input becomes the top row of the displayed image. Internally, the encoder reverses row order so the last input row is written first into the BMP pixel data block. This inversion is handled automatically. If you open the raw BMP bytes in a hex editor, the bottom row of the image appears first after offset 54.