Perspective correction wrong

[darkdragon-001]

There seem to be several issues with the code:

• It picks the minimum instead of the maximum
• It shrinks both dimensions by a factor of sqrt(2)
• For large distortion angles, this looks very wrong

AndroidScannerDemo/ScanDemoExample/scanlibrary/src/main/jni/scan.cpp

Lines 134 to 142 in ec17c27

	float w1 = sqrt( pow(x4 - x3 , 2) + pow(x4 - x3, 2));
	float w2 = sqrt( pow(x2 - x1 , 2) + pow(x2-x1, 2));
	float h1 = sqrt( pow(y2 - y4 , 2) + pow(y2 - y4, 2));
	float h2 = sqrt( pow(y1 - y3 , 2) + pow(y1-y3, 2));
	float maxWidth = (w1 < w2) ? w1 : w2;
	float maxHeight = (h1 < h2) ? h1 : h2;
	Mat dst = Mat::zeros(maxHeight, maxWidth, CV_8UC3);

Any ideas how to improve this?