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New with Photoshop CS3 and CS3 Extended is the Quick Select tool, and this tool will allow us to quickly and easily create a region of interest if there is enough color contrast in the image. Its found associated with one of the oldest tools in Photoshop, the Magic Wand tool. We click that and we can see the Quick Select tool. The best analogy is that we are basically painting a selection. For us, what an easy area to paint would be the media of this trichrome-stained coronary vessel.
Now, this is a single layer, so you don't have to worry about Sample All Layers, and we are not going to use the Auto-Enhance right now. But we are able to create a new selection, add to that selection, or subtract from that selection. Since we are painting the selection, we are able to choose a brush, and we can either increase the size or decrease it, depending on what's needed. We can also change the Hardness and Spacing, though that's of little use in this instance.
So in this case, I want to increase and decrease the size of the brush as I am moving it along the media. Remember that the Square Brackets can adjust the size of the brush. The Left Square Bracket reduces it in size, and the Right Square Bracket makes it larger. We will click down, and we will start moving around. In this case now we will decrease the size of the brush and we will just move around the media. Now in that case, I included some area I didn't want, so I can either use the Subtract from, or I could hold down the Option key or Alt key on the PC, and remove that area from the selection.
I release that, and now I am automatically adding more to the selection. I am just tracing along, grabbing the entire media. In this case, I want to decrease its size. It joined up, and now we have the media selected. That was quick and painless, though with the Quick Select tool you do want to check with Refine Edges how well the selection forms to what you want for a region of interest.
Refine Edge, and we could use a little bit of smoothing to smooth out the jagged transition. Let's turn on the Quick Mask and see if we want to contract or expand this. I think we are pretty good with a little bit of expansion. Lastly, we probably want to bring the Contrast way up and we can see what that's going to look like when we use the Mask View Mode.
We want to decrease the Radius to 0. Here we can turn on our Regular Selection View, and that is now the best fit for that selection on the region of interest, except for in one location. We hit Cancel, and now we are just going to remove a little bit of this by using our Option key on the Mac, Alt key on the PC, and just slowly remove that area, and now it fits perfectly to the tissue we wanted to measure.
We can go to Analysis > Record Measurements, but before we do that, we need to make sure that the Set Measurement Scale is correct. We want to choose the 20x Calibration and now when we do Record Measurements, it won't be measuring in pixels but in our calibrated standard. Here is our result: Area, Perimeter, Height and Width of a Bounding Box. So that's one way we can use Quick Select to create a region of interest. In the next video we are going to go over using the Magic Wand tool, which is a very automated way to create a selection if all the transitions are defined well enough.
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