BMP Image
ImagesBMP stores raster images, often without compression. It can be much larger than PNG or JPEG. Choose an export format according to whether the content is a photo, diagram or transparent image.
- What it is used for
- Raster images storing pixels
- What the file contains
- Binary data
All sections, questions and sources
Content reviewed： · Editor：Kai
Opening steps
Choose your environment or purpose to see its steps.
Menu labels and support vary by app, OS and version. Preserve the original before making changes.
Troubleshooting by symptom
- Large size: inspect dimensions and bit depth, then try a separate PNG export.
- Black transparency: BMP alpha support varies; test a PNG export when transparency matters.
- Opening failure can involve a BMP variant, compression support or an incomplete download.
- Large file: many BMPs are uncompressed; compare PNG when the workflow permits.
- Fails in one application: check its supported depths, compression and header variants.
- No transparency: BMP alpha handling varies by app; consider PNG where transparency is needed.
BMP → PNG / JPEG
- Use Save As or Export to create a PNG/JPEG copy.
- Consider PNG for text/diagrams and JPEG for photos; check dimensions and visual quality.
- Verify dimensions and colors; also check the required depth for device workflows.
JPEG is lossy and does not preserve transparency. Retain the BMP for comparison.
Color count and bit depth
Indexed BMPs may contain limited colors. Changing the output depth cannot restore missing tonal information.
Device BMPs can fail despite looking correct. Record the required internal settings.
Source for these steps：Microsoft · Bitmap Storage / Apple · Convert image file types using Preview on Mac
Inspecting the conversion
Check dimensions, color, transparency and orientation. Renaming is not image conversion.
Choose a format appropriate to the content and recipient, such as PNG for screen captures or JPEG for photographs.
Source for these steps：Microsoft · Bitmap Storage / Apple · Convert image file types using Preview on Mac
Related-format differences
| Format | Main role | Selection notes |
|---|---|---|
| BMP | Bitmap image | Check depth / compression support |
| PNG | Lossless / transparent image | Check device support |
| JPEG | Photograph sharing | Compression can affect lines and text |
Handling and security
Use an updated viewer for unfamiliar images. Check visible private information before sharing and follow upload rules.
Questions and answers
Is BMP always uncompressed?
No; BMP variants include different compression methods.
Will PNG reduce quality?
PNG is not lossy, but export settings can change bit depth or dimensions.
Does renaming to JPG reduce size?
No; the image must actually be encoded as JPEG.
Is BMP always uncompressed?
Some variants use compression; the suffix alone does not establish the encoding.
Will BMP-to-JPEG reduce size?
It often reduces photograph size but may introduce artifacts on text or lines. Compare PNG too.
Format facts: name, steward and MIME type
- Formal name
- Windows Bitmap
- Steward / specification
- Microsoft
- MIME type
- image/bmp
Primary and official sources
- Official documentationBitmap Storage
Describes BMP headers and pixel storage.
Microsoft · Link checked： - Platform documentationWindows Imaging Component Overview
Lists Windows imaging codecs, including BMP and TIFF.
Microsoft · Link checked： - Platform documentationConvert image file types using Preview on Mac
Documents Preview’s File → Export format selection.
Apple · Link checked：