PGM to RB Converter

PGM to RB — create ebooks from your content online

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Cloud Processing

The heavy lifting happens on our servers. Your device does not process anything — just upload PGM and download RB.

Any Device, Any OS

Desktop, laptop, tablet, phone — the converter handles PGM to RB equally well on every device and operating system.

Quality Preserved

Your original PGM content is preserved in the RB result. The conversion process does not introduce unwanted artifacts.

How to convert PGM to RB

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose rb or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your rb file right afterwards

About formats

PGM (Portable Graymap) is the grayscale member of the Netpbm image format family, created by Jef Poskanzer in 1988 as part of the Pbmplus toolkit for Unix systems. PGM stores single-channel intensity images where each pixel holds a gray value from 0 (black) to a user-specified maximum (typically 255 for 8-bit or 65535 for 16-bit). The format exists in ASCII (magic number P2), where pixel values are written as decimal text numbers separated by whitespace, and binary (magic number P5), where values are stored as raw bytes. Both variants begin with a header specifying the magic number, width, height, and maximum gray value. PGM was designed as the grayscale intermediate in Netpbm's convert-process-convert pipeline philosophy: source images from any format are converted to PGM, processed using Netpbm's extensive command-line tool library, then converted to the target format. One advantage is format transparency — the ASCII variant makes image data directly readable by humans and trivially processable by text tools like awk and grep, invaluable for debugging and education. The scientific and computer vision community's adoption is another strength: PGM's straightforward single-channel representation makes it a natural format for image analysis algorithms, and many academic papers and course materials use PGM examples. The format is supported by ImageMagick, GIMP, and countless image processing libraries, and remains standard input for many research tools and benchmarks.
Developer: Jef Poskanzer
Initial release: 1988
RB is the native ebook format of the Rocket eBook, one of the first commercially available dedicated e-reading devices, developed by NuvoMedia and released in October 1998. Founded by Martin Eberhard and Marc Tarpenning — who later co-founded Tesla Motors — NuvoMedia designed the Rocket eBook as a handheld device with a reflective LCD screen, capable of storing approximately ten books in its internal memory. The RB format packages HTML-based content along with embedded images, metadata, and a table of contents into a single binary container optimized for the device's limited hardware. Content was purchased and downloaded through NuvoMedia's RocketLibrarian desktop software. A notable advantage of the format was its early support for bookmarking, annotation, dictionary lookups, and adjustable font sizing — features now standard on modern e-readers but revolutionary in the late 1990s. The Rocket eBook demonstrated viable commercial demand for dedicated reading devices, paving the way for subsequent platforms from Sony, Amazon, and others. NuvoMedia was acquired by Gemstar-TV Guide International in 2000, which discontinued the device line in 2003. While RB files are largely a historical curiosity today, they can be converted to modern formats using ebook management tools, and the format remains significant as a pioneering chapter in the evolution of digital reading.
Developer: NuvoMedia
Initial release: 1998

Frequently Asked Questions

Why convert PGM to RB?

RB provides legacy ebook format — converting lets you package image content into a readable digital book format.

What apps read RB files?

Use Calibre, legacy Rocket eBook devices to open RB files. The format is well-supported across desktop and mobile platforms.

Can I read the RB file on my e-reader?

The RB format is compatible with popular e-readers. Load the file onto your device or use a reading application.

Does the conversion preserve page layout?

Visual structure is preserved where possible. The RB format adapts content flow for optimal reading on devices.

Is batch conversion to RB available?

Batch conversion is supported. Queue multiple PGM files and get separate RB ebook outputs for each one.