How I Did My Image Processing
Simple steps that will allow you to do it yourself - part 5
Now we have a set of high-spatial frequency data and we can start to pick out some details. We could extract some mid-frequency data and combine the two, and get an even clearer image. That will be our next step.
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We will now make a new blurring operation and extract a second set of spatial frequency data. Once it is done, it will look very much like the first spatial frequency data. To do it, we take that work image (that was blurred and inverted) and we blur it a bit more. Say we use an "average" operation over a 5x5 pixel area. We might do that three times. Once done, we will overlay (or stitch together) all our spatial frequency data and get something like this. Note that this is a mostly gray image- no real light or dark. in fact, the image is (as a consequence of how this process works) at exactly 1/2 the light level, or a 50% gray level. Think about adding 100% light to 100% dark and what do you get? 50% of that- gray. |
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Now we can add this information back into the first and original image. This will show us things that were too faint or subtle to notice by eye the first time. For instance, notice the faint loopy structures over the top? they were almost completely invisible before. And we can also clearly make out the clefts and lines that are present on the fossil. But enhancing sharpness often also destroys a lot of the image and we are unable to connect the noisy signals to see what is present. Wouldn't it be great if we could extract all the noise and high frequency data to see a "polished smooth" shape- the true geometry of this organism? You can, and you have already created the tools to do it. The first high-spatial frequency image is all the data you need. |
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Once we invert and subtract the high-spatial frequency data, we get this soft and blurry sort of image- but look at the shape! We can clearly and without a doubt make out that hand feature, the "eye" to the lower right, and the disc underneath that wart in the middle. We now have a pair of very nice images that tell us worlds about the fossil we are examining. |
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| The last step is
to annotate or outline the features so that they can be easily seen and
compared to other fossils. This is a very important step in
identifying something that my be in a picture that is otherwise too noisy
or complex to see what you have in it.
Or, if you are so inclined, you can amplify the contrast and add this image back to the enhanced detail image and get something that has a much more "normal" range of contrast and clearly shows the features that are faint or lost in the raw images. |
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