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Supported Formats
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Web Formats
Joint Photographic Experts Group - the most universal image format for photographs using lossy compression. Reduces file sizes 90-95% with minimal visible quality loss. No transparency support. Perfect for photos, web images, email attachments, and any scenario requiring small file sizes. Adjustable quality levels from 1-100. Standard since 1992 with universal device and software support. Ideal for photographs and complex images with many colors.
Portable Network Graphics - lossless image format supporting transparency and 16 million colors. Larger files than JPEG but perfect quality preservation. Supports alpha channel for smooth transparency. Excellent for logos, graphics with text, screenshots, and images requiring transparency. Better compression than GIF for photos. Perfect for web graphics, UI elements, and any image needing lossless quality or transparency. Standard format for web graphics since 1996.
Web Picture format - modern image format by Google providing 25-35% smaller files than JPEG at equivalent quality. Supports both lossy and lossless compression plus transparency. Superior compression algorithms reducing bandwidth usage. Native browser support (96%+ coverage). Perfect for website optimization, web images, and reducing page load times. Combines best features of JPEG, PNG, and GIF. Recommended for modern web development.
Graphics Interchange Format - image format supporting animation and transparency with 256-color limitation. Small file sizes for simple images. Perfect for simple animations, emojis, memes, and graphics with few colors. Lossless for limited palette. Inefficient for photographs (use JPEG) or high-color graphics (use PNG). Universal support since 1987. Standard format for simple web animations and reaction images.
Scalable Vector Graphics - XML-based vector format rendering perfectly at any size. Infinitely scalable without quality loss or pixelation. Small file sizes for geometric shapes and illustrations. Editable with text editors and design software. Perfect for logos, icons, diagrams, and graphics requiring scaling. Supports animation and interactivity. Standard for responsive web graphics and resolution-independent designs. Essential format for modern web icons.
Icon File Format - specialized format for Windows icons containing multiple image sizes (16x16 to 256x256 pixels). Single file provides icons for all display resolutions. Used for favicons, application icons, and Windows shell icons. Supports transparency and multiple color depths. Perfect for website favicons, Windows program icons, and shortcut icons. Standard format for Windows icons since Windows 1.0. Essential for professional Windows applications.
AV1 Image File Format - next-generation image format based on AV1 video codec providing better compression than WebP and JPEG. 20-50% smaller files at equivalent quality. Supports HDR, wide color gamut, and transparency. Cutting-edge compression technology. Growing browser support (85%+ and increasing). Perfect for future-proof web images and maximum efficiency. Better quality at smaller sizes than any previous format. Recommended for modern websites prioritizing performance.
Bitmap Image File - uncompressed raster format from Microsoft providing pixel-perfect quality with large file sizes. No compression means huge files (1MB+ for screenshots). Fast to load and display. Simple format with universal Windows support. Perfect for temporary graphics, screen captures, and scenarios where compression artifacts are unacceptable. Legacy format largely replaced by PNG. Convert to PNG or JPEG for practical use and storage.
Tagged Image File Format - flexible format supporting multiple pages, layers, and various compression methods. Industry standard for professional photography, publishing, and archival. Supports lossless compression, 16-bit color depth, and extensive metadata. Large file sizes but excellent quality. Perfect for print publishing, photo archival, professional photography, and scenarios requiring maximum quality and flexibility. Used in medical imaging and professional scanning.
Professional Formats
Photoshop Document - Adobe Photoshop's native format preserving layers, effects, masks, and all editing capabilities. Supports 16-bit and 32-bit color depths for professional work. Large file sizes due to layer data and editing information. Perfect for ongoing design projects, professional photo editing, and collaborative design work. Not suitable for final output (export to JPEG/PNG). Essential format for professional graphic design and photo manipulation workflows. Industry standard for design files.
OpenEXR - high dynamic range image format developed by Industrial Light & Magic for visual effects and animation. Stores 16-bit or 32-bit floating-point values per channel enabling enormous dynamic range. Supports multiple layers, arbitrary channels, and lossless/lossy compression. Industry standard for VFX, CGI, and professional 3D rendering. Perfect for HDR photography, compositing, and scenarios requiring maximum color precision. Used extensively in film production and high-end visual effects.
High Dynamic Range Image - format storing luminance and color information with greater range than standard images. Captures and displays brightness levels impossible in JPEG/PNG. Uses 32-bit floating-point encoding. Perfect for realistic lighting in 3D rendering, environment maps, and HDR photography. Common in game development and architectural visualization. Enables realistic tone mapping and exposure adjustment. Essential for professional lighting workflows.
DirectDraw Surface - Microsoft texture format for games and 3D applications supporting compressed textures and mipmaps. Optimized for GPU loading with hardware-accelerated decompression. Stores multiple resolution levels (mipmaps) in single file. Standard format for game textures (DirectX, Unity, Unreal). Supports various compression algorithms (DXT1, DXT5, BC7). Perfect for game development, 3D modeling, and real-time rendering. Essential format for game asset pipelines.
Truevision TGA/Targa - raster graphics format supporting 8-32 bits per pixel with alpha channel. Uncompressed or RLE compressed for fast loading. Standard format for video editing, animation, and texture mapping. Excellent color accuracy with optional lossless compression. Perfect for video frame sequences, animation frames, and game textures. Widely supported in 3D software and video editing applications. Reliable format for professional media production.
JPEG 2000 - advanced image format using wavelet compression providing better quality than JPEG at equivalent file sizes. Supports lossless and lossy compression, progressive decoding, and ROI coding. Used in medical imaging, digital cinema, and archival. Better compression artifacts than JPEG. Slower encoding/decoding. Perfect for medical imaging, digital preservation, and applications requiring superior compression. Limited web browser support.
JPEG Stereo - stereoscopic 3D image format storing left and right eye views side-by-side or top-bottom. Based on standard JPEG with special arrangement for 3D viewing. Used for 3D photography, VR content, and stereoscopic displays. Compatible with 3D TVs and VR headsets. Perfect for 3D photography, stereoscopic content creation, and VR/AR applications. Requires special viewing equipment for proper 3D effect.
Portable Float Map - floating-point image format storing HDR color data. Simple format with 32-bit float values per channel. Used in computer graphics for HDR images and height maps. Uncompressed format with large file sizes. Perfect for HDR photography processing, displacement maps, and scientific imaging. Common in 3D rendering and simulation applications. Alternative to OpenEXR for simple HDR storage.
Flexible Image Transport System - scientific image format used primarily in astronomy. Stores astronomical images with extensive metadata headers. Supports multiple data arrays and tables. Standard format for astronomical data archives. Perfect for astronomical imaging, scientific data exchange, and research applications. Used by major observatories and space agencies worldwide. Essential format for astronomical research and data sharing.
How to Convert Files
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Frequently Asked Questions
What is an OTB file and why was this format created?
An OTB file is a bitmap image format used primarily on early Nokia mobile phones and certain other GSM-era devices. “OTB” stands for Over-The-Air Bitmap, and it was designed for sending small monochrome images, caller icons, and operator logos through SMS or phone-to-phone transfers long before smartphones existed. These devices had extremely limited memory, tiny screens, and very basic graphics capabilities, so OTB provided a compact, efficient way to encode simple icon-sized images that could be transmitted over narrow-bandwidth communication channels.
OTB became a cornerstone format in the era of feature phones for personalization-small images used for welcome screens, caller ID icons, and operator logos. Its simplicity ensured it could be parsed quickly by low-powered processors with minimal RAM. Today, it survives mostly in retro mobile phone communities, firmware archives, and digital preservation projects documenting early mobile technology.
How is an OTB file structured internally?
OTB uses a straightforward binary structure optimized for monochrome mobile display hardware:
Compact Header
The header typically includes width, height, encoding type, and sometimes indexing information or Nokia-specific flags.
Monochrome Bitmap Encoding
OTB images are stored as 1-bit-per-pixel bitmaps, with pixels tightly packed into bytes to minimize file size.
No Metadata System
OTB lacks EXIF, timestamps, color profiles, or orientation metadata-everything is raw for maximum efficiency.
Row-Based Bit Packing
Pixels are stored in sequential rows, with bits corresponding directly to on/off screen pixels on early mobile LCDs.
The entire design reflects a time when every byte mattered and devices had extremely constrained graphics capabilities.
Where are OTB files still used today?
While obsolete for modern smartphones, OTB remains relevant in several niche areas:
Retro Mobile Phone Communities
Collectors and enthusiasts often use OTB when restoring or customizing old Nokia devices.
Firmware Analysis
Mobile tech historians analyze OTB assets found inside early phone firmware images.
Emulators
Nokia phone emulators use OTB to render legacy screen graphics accurately.
Digital Preservation
Archives preserving early mobile content often include OTB-format operator logos and greetings.
Retro-Themed Applications
Some retro-style apps replicate early mobile graphics using OTB images.
Embedded Systems
Low-resolution devices still use similar 1-bit bitmap structures that resemble OTB layouts.
SMS Decoder Tools
Old SMS logo transfer utilities still interpret OTB images for direct transmission.
Though far from mainstream, OTB has a small but passionate place in mobile tech history.
Why do OTB images look so simple or low-quality?
OTB was designed for monochrome screens with resolutions as low as 84×48 pixels.
The format uses 1-bit color, meaning every pixel is either fully on or fully off.
Mobile phones at the time lacked CPU power for grayscale, antialiasing, or even basic dithering.
How does OTB compare to modern formats like PNG or SVG?
OTB has no color support, no transparency layers, no compression, and no metadata-features standard in PNG and SVG.
OTB cannot scale without severe pixelation, as it is strictly a bitmap with fixed resolution.
Its sole advantage is efficiency: OTB files are extremely small and fast to decode on old hardware.
Does OTB support color, transparency, or grayscale?
Classic OTB is strictly monochrome-each pixel is black or white.
Transparency is not supported; early Nokia displays had no concept of alpha channels.
Grayscale or color variants never became part of the official OTB specification.
Why do many image editors fail to open OTB files?
OTB is a niche format used almost exclusively on early Nokia phones.
Many editors do not include parsers for 1-bit mobile bitmap encodings.
Variations across different Nokia models introduced small differences in the file structure.
Why do OTB conversions sometimes fail or distort?
Conversion problems typically stem from strict constraints in the original file format:
Incorrect Dimensions
Some converters misinterpret width/height values, producing wrongly scaled or cropped images.
Bit-Packing Issues
Errors in interpreting 1-bit pixel streams can cause broken or shifted images.
Unexpected Header Variants
Different Nokia models used slightly different OTB header fields.
No Grayscale Handling
Grayscale input images must be thresholded, often producing harsh, blocky results.
Truncated Files
Corrupted SMS transmissions or firmware dumps often contain incomplete OTB assets.
Dedicated Nokia-logo conversion tools typically handle OTB far more reliably than generic converters.
Does OTB support embedded metadata?
No-OTB includes no metadata of any kind.
It does not support orientation, DPI, timestamps, color profiles, or author information.
All meaning and context must come from outside the file.
What can OTB still be used for today?
Although outdated, OTB still has real-world niche uses:
Nokia Feature Phone Modding
Users customizing old devices still apply OTB-based logos and startup images.
Mobile History Research
Researchers studying early phone UX examine OTB assets as part of UI evolution.
Retro Messaging Demonstrations
OTB is used to demonstrate how old SMS-based picture transfers worked.
Embedded Microdisplay Testing
OTB’s simple 1-bit layout is ideal for testing tiny LCD panels or OLED control logic.
Unix Conversion Tools
Certain ImageMagick builds still support OTB for historical completeness.
Low-Power Systems
Because OTB is so lightweight, it remains useful in ultra-small embedded projects.
Operator Logo Archives
Telecom nostalgia archives often store old carrier logos in OTB format.
Protocol Emulation
SMS-over-IP emulators support OTB for authenticity in retro message transfer.
Telecom Research
Some telecom researchers analyze OTB because it reflects early content encoding for wireless networks.
Retro Digital Art
Artists sometimes use OTB limitations to create pixel-perfect monochrome designs.
Why are OTB files so small?
They use strict 1-bit-per-pixel encoding with tightly packed bits.
Image dimensions are extremely small, fitting early phone screens.
No compression layers or metadata blocks increase size.
How large can an OTB image get?
Most OTB images remain under a few hundred bytes due to dimension limits.
Nokia firmware often rejected images that exceeded device-specific pixel dimensions.
Files larger than expected often indicate corrupted data or nonstandard variants.
Can an OTB file contain multiple frames or animations?
No-OTB supports only a single static bitmap.
Early phones handled animations using multiple sequential OTB files.
Multiframe support was managed by firmware, not the OTB format.
Why do some OTB images appear mirrored or flipped?
Some old tools saved bit-packed rows in reverse bit order.
Differences in horizontal byte alignment could shift the image unexpectedly.
Some firmware variants expected vertically inverted rows, causing confusion in modern converters.
Is the OTB format still relevant today?
For modern smartphones, OTB is obsolete, but its historical importance in early mobile personalization remains significant.
Its minimalism makes it useful in microcontroller displays and instructional examples of 1-bit graphics encoding.
OTB continues to live on in retro mobile modding, emulator development, and digital archives of early texting culture.
About the OTB Format
OTB is a file format used in specific workflows. The exact characteristics depend on the implementation and chosen settings.
- Format Type
- File format
- Origin
- Industry-developed format
- Common Uses
- Various applications that support OTB
- Compression
- Depends on implementation
Sources and References
Format details on this page are based on the official specifications and documentation below.
- Image file type and format guide- MDN Web Docs