pixellate image region in camtasia for mac

PIXELLATE IMAGE REGION IN CAMTASIA FOR MAC HOW TO

The foreground image now appears as if it is on the beach. Set inputBackgroundImage to the image that shows the new background. Set inputImage to the image produced from the CIColorCube filter. Set the input parameters of the CISourceOverCompositing filter as follows: ĬIImage *result = īlend the processed source image over a background image Now that you have the color map data, supply the foreground image-the one you want the green removed from-to the CIColorCube filter and get the output image. [colorCube setValue:data green from the source image NSData *data = [NSData dataWithBytesNoCopy:cubeDataĬIColorCube *colorCube = [CIFilter Set data for cube Calculate premultiplied alpha values for the cubeĬ += 4 // advance our pointer into memory for the next color value Populate cube with a simple gradient going from 0 to 1įor (int z = 0 z minHueAngle & hsv < maxHueAngle) ? 0.0f: 1.0f

PIXELLATE IMAGE REGION IN CAMTASIA FOR MAC HOW TO

Listing 5-3 shows how to create the color cube needed for this filter recipe.įloat *cubeData = (float *)malloc (size * size * size * sizeof (float) * 4) The minimum and maximum angles need to center around that value.Ĭube map data must be premultiplied alpha, so the final step for creating the cube map is to multiply the RGB values by the alpha value you just computed, which is either 0.0 for green hues or 1.0 otherwise. Pure green is at a value corresponding to 120º. Then, for anything that’s green, you set its alpha value to 0.0. To remove green, you need to define the minimum and maximum angles around the central access that contain green hues. In that representation, you can visualize color as a pie slice and then simply remove the slice that represents the chroma-key color. In HSV, hue is represented as an angle around the central axis of a cylinder. The most straightforward way to proceed is to convert the color values in the image from RGBA to HSV values. You need to remove all the green from the image by setting green to alpha = 0.0, which makes it transparent. (You can remove a different color if you’d like.) However, this recipe requires that you remove all green from the image. The default lookup table for CIColorCube is an identity matrix-meaning that is does nothing to its supplied data. The Core Image filter CIColorCube takes color values as input and applies a lookup table to the values. Create a Cube MapĪ color cube is a 3D color lookup table. The sections that follow show how to perform each step. Use the CISourceOverCompositing filter to blend the processed source image over a background image Use the CIColorCube filter and the cube map to remove chroma-key color from the source image. Figure 5-1 The Chroma Key filter processing chainĬreate a cube map of data that maps the color values you want to remove so they are transparent (alpha value is 0.0). Removes a color or range of colors from a source image and then composites the source image with a background image. Listing 5-1 The interface for the CIColorInvert inputImage ĬIFilter *filter = , Follow the simple example shown in Listing 5-1 and Listing 5-2 to build your own filters. As its name suggests, CIColorInvert supplies vectors to CIColorMatrix that invert the colors of the input image. The CIColorInvert filter provided by Core Image is a variation on the CIColorMatrix filter. (It’s not necessary in this example because the input parameters are set values.) Override the setDefaults method, if necessary. You must prefix each input parameter name with input, such as inputImage. To subclass a filter you need to perform the following tasks:ĭeclare properties for the filter’s input parameters. Core Image implements some of its built-in filters using this technique. When you subclass CIFilter you can modify existing filters by coding them with preset values or by chaining them together. Subclassing CIFilter to Create the CIColorInvert Filter By following the subclassing procedure in Subclassing CIFilter to Create the CIColorInvert Filter, you should be able to create filters from the recipes in this chapter or venture forth to create your own interesting combinations of the built-in filters provided by Core Image. Then it describes recipes for chaining together a variety of filters to achieve interesting effects. This chapter shows how Core Image subclasses CIFilter to create the CIColorInvert filter. When you create an effect this way that you want to use multiple times, consider subclassing CIFilter to encapsulate the effect as a filter. You can create custom effects by using the output of one image filter as the input of another, chaining as many filters together as you’d like. Next Previous Subclassing CIFilter: Recipes for Custom Effects

Pixellate image region in camtasia for mac