CONVERT
Y4M → BMP
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Fast, secure Y4M to BMP conversion. No registration required.
Here is the short version — Y4M is a video container, so playback depends on the codec inside as well as the wrapper itself. Hence the need for BMP. Y4M to BMP conversion is what powers every thumbnail, every sprite sheet and every "scrubbing preview" in modern video players. Our pipeline exposes the same capability as a simple upload-and-download tool you can run from any browser. In practice Y4M is a video container, so playback depends on the codec inside as well as the wrapper itself. On the other end, BMP is the uncompressed Windows bitmap format — bulky but pixel-perfect.
YUV4MPEG2
Source formatYUV4MPEG2 (Y4M) is a simple uncompressed video format that stores raw YUV pixel data with a minimal header. It is widely used as an intermediate format for video processing and quality benchmarking where no compression artifacts are acceptable.
BMP Image
Target formatBMP is an uncompressed raster image format native to Windows. Files are large but preserve exact pixel data with no compression artifacts. Rarely used on the web due to file size.
Why convert Y4M to BMP
Image-only destinations like printed documents, favicons and email newsletters will reject Y4M outright. Extracting to BMP unlocks those channels without asking you to cut and re-render the video in an NLE.
HOW TO CONVERT
Y4M → BMP
Provide the video
Select or drop a Y4M file. The pipeline reads the header and figures out the frame timing.
Extract the still
We decode the requested frame at its native resolution and encode it as a BMP.
Save the image
Download the BMP. Original and output are auto-deleted within two hours.
Common Use Cases
Share across platforms
Send BMP files to anyone without worrying about whether they have the right software for Y4M.
Embed in documents
Drop BMP output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
BMP often produces smaller files than Y4M for web, email and storage.
Archive & future-proof
Store in a widely-supported format that will still open on future operating systems without legacy plugins.
Y4M vs BMP — Strengths and limitations
What each format does best, and where it falls short.
Y4M Strengths
- Uncompressed raw YUV — codec benchmark truth.
- Dead-simple header.
- Universal codec development support.
Limitations
- Enormous file sizes.
- Development-only — not for consumption.
- No metadata beyond basic stream params.
BMP Strengths
- Dead-simple format — trivially easy to read and write.
- Lossless and uncompressed — perfect bit-exact pixel storage.
- Universally supported in Windows applications since 1985.
- Supports 1, 4, 8, 16, 24, and 32-bit color depths.
Limitations
- Enormous file sizes — no meaningful compression in typical use.
- Not a web format — browsers support it but nobody serves BMPs over HTTP.
- No metadata support (no EXIF, no ICC profile in practice).
Y4M vs BMP — Technical specifications
Side-by-side comparison of the technical details.
Y4M
- MIME type
- video/x-yuv4mpeg2
- Extension
- .y4m
- Pixel format
- YUV 4:2:0, 4:2:2, 4:4:4
- Header
- ASCII single line
BMP
- MIME type
- image/bmp
- Extensions
- .bmp, .dib
- Compression
- None (typical); RLE 4/8 bit (rare)
- Color depths
- 1, 4, 8, 16, 24, 32 bits per pixel
- Byte order
- Little-endian
| Specification | Y4M | BMP |
|---|---|---|
| MIME type | video/x-yuv4mpeg2 | image/bmp |
| Extension | .y4m | — |
| Pixel format | YUV 4:2:0, 4:2:2, 4:4:4 | — |
| Header | ASCII single line | — |
| Extensions | — | .bmp, .dib |
| Compression | — | None (typical); RLE 4/8 bit (rare) |
| Color depths | — | 1, 4, 8, 16, 24, 32 bits per pixel |
| Byte order | — | Little-endian |
Y4M vs BMP — Typical file sizes
Approximate file sizes for common scenarios.
Y4M
- 10 sec 1080p Y4M ~600 MB
- 1 min 4K Y4M ~14 GB
BMP
- Small icon (32×32) 4 KB
- Screenshot (1920×1080) ~6 MB
- 4K image (3840×2160) ~25 MB
- Scanned A4 at 300 dpi ~25 MB
Quality & Compatibility
Colour rendering depends on the Y4M video's colour space. BT.709 HD video and BT.2020 HDR content both map cleanly into a standard sRGB BMP; true HDR wide-gamut extraction requires the specific BMP formats that support it (JPEG XL, AVIF).
Tips for Best Results
- Use batch extraction when you need a contact sheet — one BMP every 5-10 seconds gives a readable overview of any Y4M.
- Set Advanced → scale to target your destination pixel size once in the pipeline instead of resizing the BMP later in Photoshop.
- Keep the Y4M alongside the BMP so you can redo the extraction with different settings without re-uploading.
Frequently Asked Questions
Yes. The free tier accepts files up to 25 MB without registration, email capture or watermarks; paid plans go up to 2 GB. Paid plans raise the size cap, enable batch conversions and provide a REST API for automation, but nothing on the free tier is quality-limited — the output is exactly the same as on any paid plan.
Yes. The Advanced panel accepts a timestamp in HH:MM:SS.mmm and FFmpeg seeks to that exact presentation time. You can also request the first, middle or last frame shortcuts, or a full batch (one BMP per second or per N frames).
Uploads run over HTTPS, files are processed in isolated containers, and both the source Y4M and the BMP output are auto-deleted within two hours. No account is required, file contents are never logged, and KaijuConverter does not use uploads for AI training. The paid plan adds a signable data-processing agreement for regulated workflows.
Yes by default. The extracted frame is written at the same width and height as the source video. If you need a smaller image for the web, an Advanced "scale" option downsizes during the same pass so you do not have to re-encode twice.
Most files finish in well under a minute. Small images and documents are typically ready in a few seconds; large video or audio files scale roughly with duration. Upload speed from your network is usually the dominant factor, not server time.
Partially. We tone-map HDR Y4M content back to SDR when the target BMP does not support wide-gamut. For proper HDR preservation pick a modern BMP that supports it natively (JPEG XL or AVIF) and leave "preserve HDR" enabled in Advanced.
Related comparisons
See these formats side by side to understand which fits your use case best.
Related Guides
BMP Bitmap Format: The Complete Technical Guide
Everything about the BMP format: DIB header variants, pixel storage, color depths (1 to 32-bit), RLE compression, alpha channels, and BMP vs PNG vs TIFF.
Read guideBMP Format: Windows Bitmap Images Explained — Headers, Compression & Use Cases
Learn what BMP files are, how the Windows Device Independent Bitmap format works, supported colour depths, compression options, and when to use BMP vs PNG.
Read guideBMP Bitmap Format: Complete Technical Guide to Windows Bitmap Images
Learn BMP (Windows Bitmap): BITMAPINFOHEADER structure, pixel encoding, color palettes, RLE compression, and raster fundamentals for legacy graphics.
Read guideSecure & Private Conversion
Your files are encrypted during transfer, processed in isolated containers, and automatically deleted within 60 minutes. We never read, share, or store your data.