GPUImage翻译六：Demo代码

Sample applications

Several sample applications are bundled with the framework source. Most are compatible with both iPhone and iPad-class devices. They attempt to show off various aspects of the framework and should be used as the best examples of the API while the framework is under development. These include:

SimpleImageFilter

A bundled JPEG image is loaded into the application at launch, a filter is applied to it, and the result rendered to the screen. Additionally, this sample shows two ways of taking in an image, filtering it, and saving it to disk.

SimpleVideoFilter

A pixellate filter is applied to a live video stream, with a UISlider control that lets you adjust the pixel size on the live video.

SimpleVideoFileFilter

A movie file is loaded from disk, an unsharp mask filter is applied to it, and the filtered result is re-encoded as another movie.

MultiViewFilterExample

From a single camera feed, four views are populated with realtime filters applied to camera. One is just the straight camera video, one is a preprogrammed sepia tone, and two are custom filters based on shader programs.

FilterShowcase

This demonstrates every filter supplied with GPUImage.

BenchmarkSuite

This is used to test the performance of the overall framework by testing it against CPU-bound routines and Core Image. Benchmarks involving still images and video are run against all three, with results displayed in-application.

CubeExample

This demonstrates the ability of GPUImage to interact with OpenGL ES rendering. Frames are captured from the camera, a sepia filter applied to them, and then they are fed into a texture to be applied to the face of a cube you can rotate with your finger. This cube in turn is rendered to a texture-backed framebuffer object, and that texture is fed back into GPUImage to have a pixellation filter applied to it before rendering to screen.

In other words, the path of this application is camera -> sepia tone filter -> cube -> pixellation filter -> display.

ColorObjectTracking

A version of my ColorTracking example from http://www.sunsetlakesoftware.com/2010/10/22/gpu-accelerated-video-processing-mac-and-ios ported across to use GPUImage, this application uses color in a scene to track objects from a live camera feed. The four views you can switch between include the raw camera feed, the camera feed with pixels matching the color threshold in white, the processed video where positions are encoded as colors within the pixels passing the threshold test, and finally the live video feed with a dot that tracks the selected color. Tapping the screen changes the color to track to match the color of the pixels under your finger. Tapping and dragging on the screen makes the color threshold more or less forgiving. This is most obvious on the second, color thresholding view.

Currently, all processing for the color averaging in the last step is done on the CPU, so this is part is extremely slow.