5. OpenCV Tutorial - Learn Classic Computer Vision & Face Detection (OPTIONAL)/16. Arithmetic Operations - Brightening and Darkening Images.srt

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So let's get into some arithmetic operations using open.

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So what arithmetic operations are they basically adding matrices to imagery and by adding mistresses

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or subtracting matrices from or imagery.

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It has the effect of increasing brightness or decreasing brightness or intensity.

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So to do that we actually have to first create the matrix that we want to add subtract to our image

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and non-pay has actually has built in functions one called empty ones.

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This allows us to create an array which is of this dimension which is same dimensions as image here.

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And we ascended and type to unsane and to get it which is what open CBEST uses to store or image data

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and we multiply by Escuela 75.

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So if we wanted to see what this looks like let's just copy this line here.

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And run it separately in a different cell.

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And it's actually just printed here and there we go.

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So as we see these images of matrix of 75 and here of course the same dimensions as this image here.

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So using the CV to the add function it adds these two matrices here.

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Other uses function this and this image or I should say has to have to seem them actions which is why

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we follow and copied it into this one function here.

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And likewise we do it with the subtraction function here.

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So let's see how this looks when we actually run this function.

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There we go.

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This is a darkened image here substantially darker.

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And this is a and image here.

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What's important to know is that let's say we did a 175 here.

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What do you think would have happened with certainty.

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This one is even darker which means that volumes are less big.

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Bigger than 175.

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These are the only ones that show up not because everything else cost to zero which is why it's black.

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And similarly there's a lot of white points or very light coats here.

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What happens is that when you add 175 to these points it actually reaches 255 which is white as you

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can see sort of has the effect of clipping highlights in some areas here.

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Please know that we can't ever exceed 0 and 255.

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So whether we're adding when we're adding literacies to imagery.

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Keep that in mind that you will get some clipping which is what we saw in the black and white images

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here.

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So let's start doing some bitwise operations and icle and device operations and masking because that's

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essentially what you'll be using these bitwise operations for.

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They're quite handy when you have to mask images which you will see later on in this course.

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But for now we'll just enjoy this topic.

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So firstly let's create some cheaps here.

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So we're going to create a square and an ellipse here.

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Now you may be familiar with creating a rectangle or square I call it because it's seem that mentions.

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I for this one.

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However an ellipse is slightly different.

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It doesn't actually follow the same standard as a sicko.

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You can check the weapons in the documentation to get some details and one go into it in this chapter

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here.

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It's taken too much time.

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Let's just run this function and we see it here.

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So elipse are single efforts and has actually not a full of study parameters to create sort of a semi

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hemisphere type image here.

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So what we're going to do know we're going to overlay these images and using some bitwise operations

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to illustrate the different type of operations that we have.

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So let's get to it.