Dpcm codec with higher reconstruction quality on important gray levels

A method of decompressing stored image data corresponding to a frame in an image compression and storage system, the method comprising:

• decoding an encoded value corresponding to an original sample of the frame to generate a decoded value corresponding to a quantized biased residue;
• performing inverse quantization on the decoded value to generate a reconstructed biased residue;
• adding a prediction of a mapped previous reconstructed sample to the reconstructed biased residue to generate a reconstructed biased sample;
• applying a modulo subtraction to the reconstructed biased sample to generate a mapped reconstructed sample;
• and
• inverse mapping the mapped reconstructed sample to an unmapped reconstructed sample based on a high priority sample value, a bit depth of the original sample and a maximum allowed error.

An image compression and storage system comprising:

• a processor;
• and
• a processor memory local to the processor, wherein the processor memory has stored thereon instructions that, when executed by the processor, cause the processor to perform:
• mapping an original sample to a mapped sample based on a bit depth of the original sample and a maximum allowed error;
• determining a residue of the mapped sample based on a mapped previous reconstructed sample;
• applying a modulo addition to the residue to generate a biased residue;
• quantizing the biased residue based on the maximum allowed error to generate a quantized biased residue;
• encoding a value corresponding to the quantized biased residue to generate an encoded value for storage in a storage medium;
• decoding the encoded value to generate a decoded value corresponding to a quantized biased residue;
• performing inverse quantization on the decoded value to generate a reconstructed biased residue;
• adding a prediction of a mapped previous reconstructed sample to the reconstructed biased residue to generate a reconstructed biased sample;
• applying a modulo subtraction to the reconstructed biased sample to generate a mapped reconstructed sample;
• and
• inverse mapping the mapped reconstructed sample to an unmapped reconstructed sample based on a high priority sample value, a bit depth of the original sample and a maximum allowed error.