OpenCV's remap() uses a real-valued index grid to sample a grid of values from an image using bilinear interpolation, and returns the grid of samples as a new image. To be precise, let: A = an im...

Sample program that upscales 2x2 matrix to 5x5 using bilinear interpolation. Result that OpenCV produces has artifacts at the borders for such simple case. gy, gx = np.mgrid[0:2, 0:2] gx = np.flo...

The results from tf.image.resize_bilinear are quite different from cv2.resize. I found this a little bothersome. Set align_corners=True is not always reasonable because the four corners are not al...

*Note: while this post is pretty much asking about bilinear interpolation I kept the title more general and included extra information in case someone has any ideas on how I can possibly do this be...

Consider the following MATLAB code: C = [ 0 0 0 0 0 0 1 2 1 0 0 2 4 2 0 0 1 2 1 0 0 0 0 0 0 ]; pcolor( C ); shading interp; axis square Note that C is invariant under 90 degree rotations. Al...

I'm training a small (10M weights on 12K images) FCN (see e.g. Long et al, 2015). The architecture is the following (it starts with FCN8s fc7 layer): fc7->relu1->dropout->conv2048->co...

The function imagecopyresampled is useful to generate a thumbnail or resize images, while keeping aspect ratio: $fn = $_FILES['data']['tmp_name']; $size = getimagesize($fn); $width = $size[0]; $hei...

I have four 2d points, p0 = (x0,y0), p1 = (x1,y1), etc. that form a quadrilateral. In my case, the quad is not rectangular, but it should at least be convex. p2 --- p3 | | t | p | | | p0 --- p...