This is an implementation of a Scale Invariant Feature Transform (SIFT) processing pipeline in Chisel. Currently the design only produces the first few phases of keypoint identification, including multiple octaves of gaussian and difference of gaussian calculation.

To test all image stream outputs of the design with a random image, run

make Random_w_e_t

Where w, e, and t are replaced by numbers represing the width of the image, number of extrema outputs per octave, and number of taps in the gaussian blur.

Parameter bounds: t >= 3, e >= 2, w > 8\3*t

Rough utilization mapping:

• gauss = e + 3
• delaydiff = sub = e + 2
• mult = floor(t\2) * gauss
• reg/mem ~= w * (floor(t\2) * (gauss + delaydiff))
• runtime ~= O(e * (w^2 * e * t))

When this runs, you should see a printout of the SSEParams object, standard Chisel compile output, then several Check n: true, where n is the pipeline stage from 0 to 2 + gauss + diff. The Chisel tester will report PASSED if all checks are true.

Known working configurations, roughly from smallest to largest (with compile+runtime):

By default, the design uses Mem modules for large shift registers. To force it to use registers, add _r to the end of the design string (ex: Random_16_2_5_r).

To generate multiple parallel and completely independent designs, run

make VecRandom_n_w_e_t

where "n" is the number of parallel designs to run. The tester will shove different random images through each design to test them, but only actually tests for completion on the first octave. We are reasonably certain that this is OK if the individual designs work. The following VecRandom designs have been tested:

This design will process an input image in Sun Raster format (.ras, .im24, .im8) and produce an one or more debug images and a coordinate identification image. By default the design processes a input file data/in.im24 and configuration file data/control.csv, and produces output files data/outn.im24 and data/coord.im24. in.im24 is the image to be processed, and control.csv contains a comma-separated list of output streams to select. outn.im24 is the nth debug image in the list in control.csv.

After downloading the repository, and having the requirements for running Chisel (see Chisel Tutorials), you will need to produce or specify the input file and control sequence.

There are several useful test cases included in the data directory already, to use one of them add a symlink from the data directory:

ln -s smiley.im24 in.im24

The same link command must be used for default control sequences in data. Then just

make

should create an test the top-level Chisel module ScaleSpaceExtrema, producing the output image.

When adding new features, it is useful to check the sequence of data at each stage of the pipeline. The debug mode of the design facilitates this by reading a 16x16 where each pixel value is the row and column coordinate. It also sets the kernel of the gaussian modules to CenterKernel, which should pass the image through the pipeline unaltered. In this mode the design reads from data/count.im8 and data/debug.csv by default, producing images data/debugn.im8 and data/debug_coord.im24.

make debug

When switching between debug and regular mode, I suggest running

make clean

Currently you need to make sure that the 2.3-SNAPSHOT of Chisel is published locally:

sbt "publish-local"

• Multiple Octaves
• Extremum detection
• Useful coordinate output
• Unit tests