Homework Set #3 Digital Image Coding – A Hands-on Exercise

CSE 534 Homework Set #3

Problem (1) (Digital Image Coding – A Hands-on Exercise)
This exercise is intended to practice as encoding of digital image created by each student
using mobile devices. You may use any programming language to implement the encoding
process. Proper displays of the image signals at various stage of image creation, color
conversion, transform, quantization, encoding, and reconstruction are also required. Each
student is required to complete the following steps:
(a) Image Preparation:
i) Take three pictures, one outdoor, one indoor, and one portrait of your own, with
appropriate resolution selection (original color images are to be submitted)
ii) Convert the color images to grey scale images using the lossless color conversion
formula; only grey scale images are used in this homework set. (converted grey scale
images are to be submitted)
iii) Subsample the original images properly and convert them (potentially additional crop)
into 1024 × 1024 image (subsampled images are to be submitted)
(b) Image Encoding:
For each 1024 × 1024 image, perform the following:
i) For each 8 × 8 block, perform DCT transform, quantization, and entropy coding;
Standard JPEG routines may be called to carry out these operations.
ii) Three different quantization settings should be selected and applied to each image
iii) Standard JPEG entropy coding tables are to be used for encoding the quantized DCT
coefficients
iv) Compute the total bits used for each image and calculate the compression ratio
v) Explanations should be given for the selection of quantization tables
(c) Image Decoding/Reconstruction:
i) Reconstruct all three images based on the bitstreams generated from image encoding
(All three reconstructed images are to be submitted)
ii) Compute the PSNR of the reconstructed images (PSNR values are to be submitted)
iii) Discussion on the selection of quantization settings on the compression ratio (original
size over compressed size) (Discussions are to be submitted)
iv) Discussion on the selection of quantization settings on the quality of compressed
images (Discussions are to be submitted)
(d) Brief report including all “to be submitted” items as well as all runnable codes and
reference codes should be submitted.
(e) Important Notice: Only standard commercial software functions may be called. Any
routines developed by any individual cannot be called or adopted.