Assembly |
 |
Computer Organization and Assembly Languages, Fall 2005
|
Jump to...
assignment #1
|
Assignment #3: Box FilterAssigned: 2005/11/17Due: 2005/12/06 grade DescriptionSmoothing filters are useful image processing tools for blurring and for noise reduction. They use spatial coherence and pixel value homogeneity of a pixel's neighborhood as bases. Noise-cleaning techniques detect lack of coherence and either replace the incoherent pixel value by something more spatially coherent by using some or all of the pixels in a neighborhood containing the given pixel or smooth the pixel value with others in an appropriate neighborhood. The operator that computes the equally weighted average is called the box filter operator.Given an image f, the box filter operator with a (2M+1)X(2N+1) smoothing neighborhood is defined by  where k(r, c) represents the pixel value of the filtered image k at the r-th row and the c-th column. Although directly implementing the above function produces the correct filtering result, this naïve method is very slow. Since such image-processing techniques usually have to meet the timing constraint for interactive playing, please try to come up with some ways to improve the speed. SpecificationYou have to implement a procedure called blur using assembly. This function should accept a pointer pointing to the image data, a pointer pointing to the output destination, the size of the kernel, the width of the image, and the height of the image. The filtering result should have been written back to the memory when this function returns. A skeleton code looks like:
.386
.model flat
option casemap :none
.data
tmp DWORD 0
.code
_blur PROC PUBLIC
push ebp
mov ebp, esp ; build stack frame
; variables in stack
; [ebp+24] image height (the 5th argument)
; [ebp+20] image width (the 4th argument)
; [ebp+16] kernel size (the 3rd argument)
; [ebp+12] pointer to the output image (the 2nd argument)
; [ebp+8] pointer to the input image (the 1st argument)
; [ebp+4} return address
; [ebp] previous ebp
; begin blurring operation
; WRITE YOUR OWN CODE HERE
; end blurring operation
mov eax, tmp
leave
ret
_blur ENDP
END ; file ends here
In hw3.zip, you can find the files you might need
and main.c where other functions are implemented.
They are used to process the image-I/O tasks (24-bit BMP only) and do
timings, and you don't need to modify them.
To simplify your task, the main procedure actually read in a 24-bit BMP,
convert it to a grey image and pass the grey image to your procedure.
Hence, you should assume that you are working on a grey-level image.
When your work is done in blur.asm, execute "nmake" and the executable file
"blur.exe" will be built. Then execute "blur.exe INPUT_FILENAME
OUTPUT_FILENAME" and you will have the filtered image named OUTPUT_FILENAME
and CPU cycles you've used.
A function called c_blur() in main.c is a C implementation of the box filter. You can use it to verify your result. To verify your result, you can compare the CRC32 or MD5 checksums of the filtering results generated by c_blur and your own procedure. To avoid collision, we will use MD5 checksum to check your results. You can find a MD5 calculator at http://www.fourmilab.ch/md5/ (a copy of md5.exe is attached in hw3.zip). For example, the MD5 checksum of the "sample1_out.bmp" in hw3.zip is AF6A54367FE4F0DAC5FBA9F562F38DB0. GradingAs the previous assignment, you will get 80 points if you implement this procedure correctly. Another 0~20 points will be added to your grade depends on the speed of your program and 0~10 points depends on the code size.Submission
|
|||||||
|
|
|||||||