OTB is a bitmap format for mobile devices, used for operator logos and graphics sent via SMS.
PGM (Portable Graymap) is a grayscale image format from the Netpbm family.
FreeFileConvert uses tuned encoding for OTB to PGM conversions, preserving clarity while trimming file size. Finished audio streams instantly across phones, tablets, desktops, and modern browsers without extra tweaks.
Upload OTB files from desktop, tablet, or cloud storage, queue multiple jobs, and let the converter finish autonomously. Return whenever convenient to download synchronized PGM results on any device you rely on.
Process up to 5 files sized 1000 MB per batch without splitting queues manually. Mixed-format uploads convert together, producing consistent PGM audio with dependable progress tracking.
OTB images are small monochrome bitmaps optimized for mobile transmission.
PGM files support 8 or 16-bit grayscale with ASCII or binary encoding.
Upload your image file in the OTB format from your device, Dropbox, or Google Drive.
Select PGM as the output format and click Convert. Adjust optional settings if needed.
Download the converted image file. Each file stays available for up to 5 downloads.