Review of Lossy Grayscale Image Compression using Spatial Pixel Based Techniques

Image compression is crucial, looks like enabling technology of daily applications, such as websites, mobile phones, social media, messaging and e-mail. Various techniques available today, but the standard one exploits generally the frequency domain especially JPEG, JPEG2000, namely DCT/DWT respectively. This review paper concerned with pixel-based techniques of spatial domain base which still under study and development that composed of three components mean, index and residual there's few works related to, that attempt to enhanced or improved with efficient encoder techniques, by incorporating the frequency domain of DWT base to compress residual part with hierarchal quantizer, hard thresholding, MMSA to be hybrid techniques, or by exploits LSV/MSV isolation, double differential pulse code modulation with mixed symbol encoder image compression, lossless/lossy, transform/spatial coding, JPEG, and PBT