Jpeg2BW software converts JPEG color images to high-precision grayscale images with ease.
The converted black & white pictures are ultimately encoded to a 16bpp grayscale bitmap file, providing about 10 accurate bits for each pixel rather than 8 with current methods. Consequently, the pictures produced by Jpeg2BW should render roughly 1,000 significant levels of gray, far more than the typical 256 levels.
When reading the JPEG file, Jpeg2BW utilizes libjpeg to get the job done. The JDCT_FLOAT method is used for the discrete cosine transform, according to the djpeg tool manual. The float method is marginally more precise than the int method, but much slower. It's worth noting that results of the floating-point approach may vary somewhat across devices, while the integer methods should generate consistent results across the board.
On the other hand, when converting the picture to the RGB colorspace, Jpeg2BW doesn't use the libjpeg. The library is instructed to leave the picture in its original YCbCr format with 8-bits per channel. When the library converts the picture to the RGB colorspace, values are rounded to the nearest integer, something Jpeg2BW avoids by working with more accurate values.
While computing in double precision, the tool merges two different black and white layers with a mask made from a saturation layer. Users can select various images with options from the command line while also applying a curve to the mask for enhanced precision.
All things considered, Jpeg2BW is an excellent tool for photographers who require highly accurate grayscale images. It's written in C and uses two libraries, libjpeg and guile, which can be compiled on a wide range of systems, making it accessible to most users.
Version 0.4.2: N/A