What is the INT file format?
.int files store black-and-white monochrome bitmap images in the SGI Image File Format. The format was developed by Silicon Graphics, Inc. (SGI), a company known for manufacturing high-performance workstations and graphics processing hardware.
The .int extension name is derived from the word "integer," reflecting that image pixels are stored as integer samples. .int is the single-channel grayscale variant of the SGI image family, which also covers .bw, .rgb, and .sgi files for other color depths and channel counts. All SGI images open with a 2-byte magic number 01 DA (big-endian) and carry a fixed 512-byte header encoding image dimensions, bits per channel (8 or 16), and a storage flag that selects either verbatim or RLE-compressed output. Maximum image size is 65,535 × 65,535 pixels. The format originated on IRIX-based SGI workstations in the 1980s; PNG and TIFF have largely replaced it for new grayscale work.
Security & safety
RISK: LOWAn SGI .int image is raster data, not executable code, so opening one is safe. The only real issue is non-malicious confusion: a .int that's actually Unreal-game text or a Delphi file won't open as an image (open it in a text editor instead). As always, verify the true extension and origin if a file arrived unexpectedly.
Format details
in a nutshellFULL NAMESGI Image File (Silicon Graphics, monochrome variant)aka Silicon Graphics Image, SGI RGB image
DEVELOPERSilicon Graphics, Inc. (SGI)since 1980s (SGI IRIS image format, Paul Haeberle's SGI Image File Format spec)
CATEGORYRaster Image Files
MIME TYPEimage/x-sgi
TYPESilicon Graphics raster image (binary); .int = grayscale/black-and-white variant
STANDARDOpen · royalty-free
This extension is also used by…
- Unreal Engine localization (.int) - INI-style English localization/config files for Unreal Engine games (the 'int' = international); plain text, opened with a text editor, unrelated to images.
- Delphi interface file (.int) - Borland/Embarcadero Delphi saved interface/unit interface data with .int; a developer text file, not an image.
- Generic intermediate/integer data (.int) - Various programs use .int for intermediate or integer/numeric data dumps; meaning is application-specific.
MAGIC BYTES · FILE SIGNATURE
OFFSET
0001
HEX
01DA
ASCII
··
SGI image files (.sgi/.rgb/.rgba/.bw/.int/.inta) all start with the 2-byte magic 01 DA (big-endian short = 474). Bytes that follow encode storage (0=verbatim, 1=RLE), bytes-per-channel, dimension count, width, height, and channel count. The .int / .bw variants store a single (grayscale/black-and-white) channel; .rgb/.rgba store color. So 01 DA identifies the SGI family; the channel count distinguishes the monochrome .int from color SGI images.
Programs that open INT files
Windows3 apps
XnView MP
Free Open the .int in XnView - it reads the SGI image family; Save As PNG/TIFF to convert. 
macOS2 apps
Apple Preview
Built-in Preview opens many SGI images; if it can't, use XnView or convert with ImageMagick. 
Linux2 apps
ImageMagick
Open-source Run 'convert file.int out.png' or 'display file.int'; SGI support is built in. 
Technical details
deep spec| Format family | SGI Image File Format (IRIS image format) |
| Grayscale channels | 1 channel (intensity only); color siblings `.rgb` and `.rgba` carry 3-4 channels |
| Magic bytes | `01 DA` hex (big-endian 16-bit = 474) at byte offset 0, shared by all SGI image variants |
| Header size | 512 bytes fixed, encoding magic, storage mode, BPC, XSIZE, YSIZE, ZSIZE, pixel min/max, and image name |
| Bits per channel | 8 or 16 bits per channel (BPC field in header) |
| Maximum dimensions | 65,535 × 65,535 pixels (XSIZE and YSIZE are 16-bit unsigned fields) |
| Compression | Storage mode 0 = verbatim (uncompressed); storage mode 1 = RLE with per-scanline offset and length tables |
| Byte order | Big-endian (network byte order), consistent across all SGI image variants |
| Encoding | Binary |
| MIME type | `image/x-sgi` (also `image/sgi` and `image/x-rgb`) |
| Color model | Grayscale (luminance only); no color channels stored |
| Origin platform | SGI IRIS workstations running IRIX (1980s); format specified by Paul Haeberle of SGI |
| RLE scan-line structure | When compressed, per-scanline start-offset and length tables precede the compressed pixel data |
| Related SGI variants | `.bw` (grayscale alias), `.inta` (grayscale + alpha), `.rgb` (color), `.rgba` (color + alpha), `.sgi` (general) |
| Superseded by | PNG and TIFF for modern grayscale storage; the SGI format is considered legacy |
| Typical file size | ~10 KB to ~20 MB depending on resolution; RLE mode significantly reduces size for uniform-area images |
| Released | 1980s (SGI IRIS image format, Paul Haeberle's SGI Image File Format spec) |
| Latest version | SGI Image File Format (final spec, 1994) |
| Open standard | Yes · royalty-free |
| Specification | media.xiph.org |
INT conversions
Possible
.INT .PNGGUIDE
Yes - open the .int file in XnView MP (free, Windows/Mac/Linux) and save it as PNG in one step.
How to convert
.INT .JPGGUIDE
Yes -- open the .int file in XnView MP or IrfanView and save as JPG.
How to convert
.INT .TIFGUIDE
Yes - open the .int in XnView MP and use Save As to export it as TIFF in seconds.
How to convert
.INT .BMPGUIDE
Yes - open the .int in XnView MP or IrfanView and save it as BMP in a few clicks.
How to convert
.INT .SGIGUIDE
Yes, INT converts to SGI easily in XnView MP or ImageMagick because both extensions are the same underlying…
How to convert
Community Q&A
asked by usersNo questions yet - be the first to ask about INT files.
Frequently asked questions
What is a .int file?
It depends on the source. In this (image) sense it's a Silicon Graphics SGI raster image - the grayscale variant of the SGI/IRIS format. The same extension is also used by Unreal Engine localization and Delphi as text files, which are unrelated.
How do I open an SGI .int image?
Use a flexible image viewer: XnView MP or IrfanView on Windows, XnView or Preview on Mac, ImageMagick or GIMP on Linux. They read the SGI image family and can convert it to PNG/TIFF.
How do I convert a .int image to PNG?
Open it in XnView or IrfanView and Save As PNG, or run ImageMagick ('convert file.int out.png'). PNG is the best modern, lossless replacement for the legacy SGI format.
My .int file opens as text/gibberish - why?
Then it isn't an SGI image - it's probably an Unreal Engine localization/config file or a Delphi file, both of which are plain text. Open it in a text editor (Notepad/Notepad++) instead of an image viewer.
Is .int the same as .sgi or .rgb?
Yes - .int, .bw, .sgi, .rgb and .rgba are all the SGI image format; the difference is the number of channels (.int/.bw are grayscale, .rgb/.rgba are color). They share the 01 DA magic.
References
1SGI Image File Format v1.0 (Paul Haeberle, SGI)media.xiph.org
2XnView MP - free multi-format image viewerwww.xnview.com
