What is the HDP file format?
.hdp files store raster images in Microsoft's HD Photo format, introduced in 2006 alongside Windows Vista. HD Photo - also marketed as Windows Media Photo or WMPhoto - was developed as a significant step up from JPEG, delivering roughly twice the compression efficiency at equivalent visual quality while adding features absent from standard JPEG.
The format uses a TIFF-like IFD (Image File Directory) container with a tile-based codec built on a two-stage lapped overlapping biorthogonal transform, which reduces the blocking artifacts common in standard JPEG. Both lossy and lossless compression are supported, along with alpha channel transparency and extended bit depths from 8-bit up to 32-bit float per channel, enabling full HDR and wide color gamut imagery.
Files carry the magic bytes 49 49 BC 01 - the little-endian II marker familiar from TIFF, followed by the HD Photo signature 0xBC 0x01. Three closely related extensions exist: .hdp for the standard decoded image, .wdp for the Windows Media Photo branding variant, and .jxr for files assigned the name after ISO standardization (JPEG XR, ISO/IEC 29199-2:2012).
Native browser support is limited: Internet Explorer and legacy Edge recognized the format, but Chrome and Firefox do not natively. Windows Photos and IrfanView open .hdp files without additional plugins. For modern high-efficiency workflows, JPEG XL (.jxl) has emerged as the next-generation successor.
Security & safety
RISK: LOWStandard image format; no executable code. Open via Windows WIC stack. No known security issues specific to HDP beyond general image codec vulnerability surface.
Format details
in a nutshellPrograms that open HDP files
Windows5 apps
Microsoft Windows Photos
Built-in Double-click the HDP file - Windows Photos opens it via built-in WIC support (Vista+). 
Adobe Photoshop
Paid Open via File → Open; Photoshop can read HDP through the Windows WIC bridge on Windows. 
macOS1 app
Adobe Photoshop
Paid Photoshop on macOS may open HDP via WIC on Windows only; macOS support is limited - convert first using a Windows machine or online converter. Technical details
deep spec| Container format | TIFF-like IFD (Image File Directory) with tile-based structure |
| Compression | Overlapping biorthogonal transform (two-stage lapped transform); supports both lossy and lossless modes |
| Color depth | 1-32 bits per channel; supports 8-bit, 16-bit, 32-bit float; up to 128 bpp total (RGBA float) |
| HDR support | Yes - 32-bit float per channel enables high dynamic range and wide color gamut imagery |
| Alpha channel | Yes - separate alpha plane stored in the IFD container |
| Byte order | Little-endian (TIFF LE marker `II` = bytes 49 49) |
| Magic bytes | `49 49 BC 01` at offset 0; string `WMPHOTO\0` also appears at offset 90 in the container header |
| MIME type | `image/vnd.ms-photo`; also registered as `image/jxr` |
| Maximum dimensions | Up to 4,294,967,295 × 4,294,967,295 pixels (32-bit dimension fields) |
| Tiling | Image divided into tiles for progressive decoding and partial region access |
| Metadata | IFD tag-based metadata, compatible with TIFF tag conventions |
| ISO standard | Standardized as JPEG XR (ISO/IEC 29199-2:2012) after submission to the JPEG committee |
| Compression efficiency | Approximately 2× better than JPEG at equivalent perceived quality |
| Released | 2006 (Windows Vista / HD Photo 1.0) |
| Latest version | HD Photo spec 1.0 (2006); standardized as JPEG XR 2009 |
| Open standard | Yes · royalty-free |
| Specification | learn.microsoft.com |
HDP conversions
Community Q&A
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