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Learn OpenCV 4 by Building Projects - Second Edition by Prateek Joshi, Vinicius G. Mendonca, David Millan Escriva

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Lomography effect

In this section, we are going to create another image effect, which is a photograph effect that is very common in different mobile applications, such as Google Camera or Instagram. We are going to discover how to use a look-up table (LUT). We will go through LUTs later in this same section. We are going to learn how to add an over image, in this case a dark halo, to create our desired effect. The function that implements this effect is the lomoCallback callback and it has the following code:

void lomoCallback(int state, void* userData) { Mat result; const double exponential_e = std::exp(1.0); // Create Look-up table for color curve effect Mat lut(1, 256, CV_8UC1); for (int i=0; i<256; i++) { float x= (float)i/256.0; lut.at<uchar>(i)= ...

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