A Grayscale Semi-Lossless Image Compression Technique Using RLE

This paper presents a new compression technique based on Run-Length Encoding scheme (RLE). The technique is semi-lossless and utilizes pixel value rather than bit value. The encoding process starts by mapping the colors of an image to a vector where each value of the vector is decimal ranging from 0 to 255. To maximize the efficiency of the decimal RLE, the 4 LSB of each of the values will be reset and utilized for compression purposes. Then, the RLE is applied on the result vector to obtain a new vector of pairs on the form , where each item consists of 8 bits. The frequency of occurrences is stored in the 4 LSB of the color value so as to reduce the total size of the image. The decoding process reverses the encoding process steps to obtain the original image. The experimental results showed that the technique has achieved high compression ratio using different images with multi-features.