How to Convert HEIC to PGM

PGM (Portable Graymap), part of the Netpbm family, stores grayscale image data at 8 bits per pixel with no color channels at all, designed as a simple lowest-common-denominator format for academic and research software. Converting a color iPhone photo from HEIC to PGM strips out all color information, leaving only the grayscale luminance values, which is exactly what's needed when a computer vision pipeline or processing script specifically expects grayscale input rather than HEIC's full-color, HEVC-compressed data.

This kind of conversion is common in research and coursework settings where the specific colors in an image don't matter as much as having a simple, well-documented format that's easy to parse directly without needing modern codec support.

1. Install Turbo Batch Image Converter Pro on your Windows PC.
2. Open the app and select Batch Mode for multiple files, or Individual Mode for a single HEIC file.
3. Drag your HEIC file or folder into the app window, enabling recursive folder scanning if needed.
4. Set the "From" format to HEIC and the "To" format to PGM.
5. Click Convert. PGM files are written to the output folder, fully offline.

• 100% offline — your photos are never sent to any server
• Bulk conversion of entire iPhone photo libraries in one pass
• Produces standard PGM files compatible with Netpbm-based research and processing tools
• Multi-core processing for fast handling of large batches
• Option to delete original HEIC files automatically once converted
• No recurring subscription or hidden upload limits