If you aren't moving at a snail's pace, you aren't moving at all. -Iris Murdoch
Saturday, March 16, 2013
Using Photoshop for Stream Table Image Analysis
Yet another wonderful thing about the color-coded plastic media is the ability to analyze stream features over time. The colors tend to organize themselves into patterns based on where the water is flowing that correspond to areas of erosion, transport, and deposition. My hope is that I can use these colors to define active/abandoned channels in each time lapse frame - stacking frames will show how those channel patterns over time. But how to simplify the images? One of the challenges lies in the fact that the yellow sediment contains some red hues - a simple saturation boost would make the yellows pop out too much. So I grabbed a picture of the stream table and tried out some Photoshop filters and adjustments to simplify the image. I've put them into an animated gif to show the differences.
I've noticed that the smallest red grains tend to show up in areas of scouring, while the white and yellow are often the first to move and the first to be deposited. Some of these adjustments really help pull out the yellow and red. Now it's time to get a time-lapse sequence and try some time series analysis.
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If you have access to ArcGIS 10 with the Spatial Analyst extension you could try using the image classification toolbar. If the RGB values are distinct enough you might be able to get it to map dominantly yellow, red, etc. areas.ReplyDelete
I played around with "posterize" in Photoshop too. I think ImageJ might also be able to handle something similar.ReplyDelete
Matt, color saturation and contrast on your original don't look very good; try to maximize that if you can. Cool stuff.ReplyDelete
This looks like a really cool idea - let me know what ends up working! Can't wait to see!ReplyDelete
I grabbed a quick shot with a point & shoot - color/contrast will be first to get adjusted.
I'm with Roger on this one. I've successfully used Spatial Analyst to classify the sediment. However ArcGIS is pricey. I think you could also do it with Multispec which is free from Purdue (https://engineering.purdue.edu/~biehl/MultiSpec/). I'll try it out and report back.ReplyDelete
Thanks for the suggestion on Multispec. The Kinect produces grayscale "PGM" files that are used for depth measurements, but knowing that ImageJ focuses on RGB only makes Photoshop (or GIMP, perhaps) worth continuing with.ReplyDelete