First released in 1998, the Djvu file format is an alternative open file format for scanned document storage. It is specifically targeted at documents that possess text, vector graphic drawings, photos, and colored images. The format's main selling point is its high quality authoring with minimum storage space making it popular in the distribution of magazines, comics, and ebooks. This fact places it in direct competition with the pdf format by Adobe Systems. The text layer in the Djvu file format supports optical character recognition which allows for text selection, copying, and pasting from .djvu files to other text processing applications. Free browser plugins are available for most major internet browsers which allows hosted .Djvu files to be opened directly through compatible browsers.
The .ppm file extension is used for Portable PixMap format files and is intended to be an intermediate format that can be used in the development and conversion of other file formats. This format was specifically designed so that it could easily be exchanged between various platforms. It is very simple but not very storage efficient. Before the PPM format was introduced, Jef Poskanzer invented the PBM format in the year 1980 for transmission of monochrome bitmaps as ASCII text in email messages. He also developed a tool library for easy conversion of the PBM files to other graphical formats and vice versa. This library was called Pbmplus and was released in 1988. Later Poskanzer developed the PPM format along with the PGM format and the requisite tools that were added to Pbmplus.
FreeFileConvert uses tuned encoding for DJVU to PPM conversions, preserving clarity while trimming file size. Finished audio streams instantly across phones, tablets, desktops, and modern browsers without extra tweaks.
Upload DJVU files from desktop, tablet, or cloud storage, queue multiple jobs, and let the converter finish autonomously. Return whenever convenient to download synchronized PPM results on any device you rely on.
Process up to 5 files sized 1000 MB per batch without splitting queues manually. Mixed-format uploads convert together, producing consistent PPM audio with dependable progress tracking.
The file format has a three pass compression technique in which single scanned images are divided into three separate images and compressed individually. The images are separated into background, foreground, and mask images. The Djvu file format then makes use of IW44, a wavelet based compression algorithm, to compress background and foreground images while the mask image is compressed using JB2 encoding.
A .ppm extension file comprises of two parts which include the header and the image related data. The header, in turn, is distributed into three parts that are demarcated by line feeds. The first line comprises of the magical PPM identifier which can either be P3 for the ASCII version or P6 for the binary version, and the next line has the image's height and width displayed in ASCII characters and the last line indicates the maximum color value of the pixels. The image data formatting is dependent on the magical identifier, given in the first line of the header. Each pixel consists of 3 decimal values ranging from 0 to the specified maximum value written in ASCII characters. The 0 in the decimal values denotes that the color is not present or is turned off and the maximum value denotes that the color is at its maximum level. Conventionally the image data is stored in a left to right and top to bottom order with each pixel being stored as a byte. The usual RGB (Red ñ Green ñ Blue) order is followed to store the components.
Upload your document file in the DJVU format from your device, Dropbox, or Google Drive.
Select PPM as the output format and click Convert. Adjust optional settings if needed.
Download the converted image file. Each file stays available for up to 5 downloads.