Grayscale output
Colour is converted to grayscale using linear-sRGB luminance and the sRGB transfer curve. Colour channels and transparency are not retained.
Convert JPEG to PGM
- In your browser
- No upload
- Private by design
What happens when you convert JPEG to PGM?
Lossless sample storage
Netpbm stores these samples without compression. Reducing colour, thresholding or changing maxval can still lose information before storage; text and binary representations change the layout, not its image meaning. PGM can store its supported image samples without lossy compression. This applies after rendering and sample conversion: it does not guarantee preservation of source precision, colour space or document structure, and cannot undo earlier losses.
JPEG
Source
JPEG
Joint Photographic Experts Group
Compression: LossyTransparency: NoMetadata: Exif, ICC
A familiar format for photographs. JPEG keeps files compact by trading a little image detail for broad compatibility.
Explore JPEG format →PGM
Target
PGM
Portable Graymap
Compression: UncompressedTransparency: NoMetadata: Header, Comments
Portable Graymap: simple uncompressed raster samples for image-processing pipelines.
Explore PGM format →Is JPEG → PGM right for you?
Good choice when
- PGM fits your delivery use: Grayscale images & masks.
- Your processing pipeline explicitly needs grayscale samples.
- You need lossless storage of the rendered samples supported by PGM.
- You can validate the destination’s sample precision and colour interpretation.
Probably not when
- Colour distinctions carry information you need to retain.
- You expect lossless encoding to restore lost details or editing structure.
- You require identical samples without a defined colour and precision policy.
JPEG to PGM conversion details
- Grayscale output
- Colour is converted to grayscale using linear-sRGB luminance and the sRGB transfer curve. Colour channels and transparency are not retained.
- Lossless sample storage
- Netpbm stores these samples without compression. Reducing colour, thresholding or changing maxval can still lose information before storage; text and binary representations change the layout, not its image meaning. PGM can store its supported image samples without lossy compression. This applies after rendering and sample conversion: it does not guarantee preservation of source precision, colour space or document structure, and cannot undo earlier losses.
- Sample precision & colour
- Pixel conversion only. Original EXIF, GPS, XMP and ICC profiles are not copied; processing uses 8-bit display pixels.
- Metadata & colour
- Pixel conversion only. Original EXIF, GPS, XMP and ICC profiles are not copied; processing uses 8-bit display pixels.
- Compression
- JPEG: Lossy → PGM: Uncompressed JPEG: Typical JPEG files are lossy. The original standard also defines a separate lossless mode; it is not the usual web or camera JPEG. PGM: Netpbm stores these samples without compression. Reducing colour, thresholding or changing maxval can still lose information before storage; text and binary representations change the layout, not its image meaning.
- Colour depth
- PGM: maxval up to 65535
- Dimensions
- Rendered image dimensions are retained within the converter limits; this tool does not offer resizing. Orientation handling depends on the source decoder.
- Metadata
- Pixel conversion only. Original EXIF, GPS, XMP and ICC profiles are not copied; processing uses 8-bit display pixels.
Common questions
Will PGM keep the source colours?
Colour is converted to grayscale using linear-sRGB luminance and the sRGB transfer curve. Colour channels and transparency are not retained.
Does lossless output mean an unchanged source?
Netpbm stores these samples without compression. Reducing colour, thresholding or changing maxval can still lose information before storage; text and binary representations change the layout, not its image meaning. PGM can store its supported image samples without lossy compression. This applies after rendering and sample conversion: it does not guarantee preservation of source precision, colour space or document structure, and cannot undo earlier losses.
Are bit depth and colour values guaranteed to match?
Pixel conversion only. Original EXIF, GPS, XMP and ICC profiles are not copied; processing uses 8-bit display pixels.
Will metadata and colour profiles be retained?
Pixel conversion only. Original EXIF, GPS, XMP and ICC profiles are not copied; processing uses 8-bit display pixels.