Image Compression of Original Grayscale Images Using DCT Coefficient Retention

This process utilizes image compression techniques to reduce data volume in digital images. For original grayscale images, we implement an 8×8 block-based Discrete Cosine Transform (DCT) where we retain either only the DC coefficient or the first 4, 8, and 16 transform coefficients (combining DC and AC components). These preserved coefficients then undergo Inverse Discrete Cosine Transform (IDCT) to reconstruct the compressed images. Implementation typically involves dividing the image into 8×8 pixel blocks and applying DCT using matrix operations. The compression strategy employs coefficient thresholding where higher-frequency AC coefficients are discarded based on quantization tables. Key functions would include dct2() for forward transformation and idct2() for reconstruction, with zigzag scanning to prioritize low-frequency coefficients. This approach significantly reduces data storage requirements while maintaining acceptable image quality, thereby improving transmission efficiency and processing performance for digital imaging systems.