Why convert ITHMB to BMP?
An ITHMB file is Apple's internal thumbnail cache from older iPods, iPhones, and iPads; it packs many small raw preview images without standard headers, making it unreadable in ordinary image viewers. BMP is an uncompressed raster format chosen when a downstream tool specifically requires it, though JPG or PNG are smaller and more practical outputs from the same extractor.
How to convert ITHMB to BMP
iThmb Converter APP
Add the .ithmb file to iThmb Converter, set the output format to BMP, choose an output folder, and click Convert; the tool extracts each thumbnail as a separate .bmp file.
GraphicConverter X APP
Open the .ithmb file in GraphicConverter, specify the raw pixel dimensions and pixel format when prompted, then use File > Save As and choose BMP.
Programs that convert ITHMB
About these formats
.ITHMB
Apple iPod/iPhone/iPad Thumbnail Cache
An ITHMB file is a thumbnail cache that older Apple iPods, iPhones, and iPads generated when you synced photos through iTunes. It is not a regular image - it packs dozens of small previews…
Open .ITHMB details →
.BMP
Windows Bitmap Image
A BMP file is a Windows Bitmap - a simple, usually uncompressed raster image developed by Microsoft. Every major OS and image viewer opens it with no extra software (double-click works).…
Open .BMP details →Quality & what to watch
- Output is low-resolution: ITHMB thumbnails were sized for the photo-grid UI on older devices - typically a few hundred pixels wide, not original camera resolution.
- BMP is uncompressed, so even a small thumbnail produces a disproportionately large file; PNG or JPG are more practical formats at the same resolution.
- ITHMB stores raw pixel data with no per-image header; the extractor uses the filename to determine dimensions and pixel format - do not rename the
.ithmbfile before converting.
