CS194-26: Frequencies and Gradients

Karl Cempron
cs194-26:aeg

This project will highlight topics in hybrid blending, multiresolution blending, and poisson blending. Further details can be found at cs194-26/project3.

Part 1.1 Sharpening

The Breakdown

As a warm up, I thought that I would take my "professional" profile picture and try to make myself look sharper! The process starts by taking the original image and smoothening it via a gaussian filter. The detailed image is than extracted from original - smoothed. Finally we re-add the detailed image (times some alpha "a") back to the original.

Part 1.1 Images

Part 1.2 Hybrid Blending

The Breakdown

Hybrid images are static images that change in interpretation as a function of the viewing distance. The basic idea is that high frequency tends to dominate perception when it is available, but, at a distance, only the low frequency (smooth) part of the signal can be seen. By blending the high frequency portion of one image with the low-frequency portion of another, you get a hybrid image that leads to different interpretations at different distances.

Part 1.2 Images

Part 1.3 Gaussian and Laplacian Stacks

The Breakdown

For this part, we take an image and create two stacks through continous application of the gaussian filter on the image and then subtracting the original from the filtered image to get the laplacian. Through this process we are able to see the high pass image and low pass image separately.

Part 1.3 Images

Part 1.4 Multiresolution Blending

The Breakdown

The goal of this part of the project is to blend two images seamlessly using a multi resolution blending. An image spline is a smooth seam joining two image together by gently distorting them. Multiresolution blending computes a gentle seam between the two images seperately at each band of image frequencies, resulting in a much smoother seam.

Part 1.4 Images

Part 2.1 Gradient Domain Processing

The Breakdown

This project explores gradient-domain processing, a simple technique with a broad set of applications including blending, tone-mapping, and non-photorealistic rendering. For this warmup, we'll compute the x and y gradients from an image s, then use all the gradients, plus one pixel intensity, to reconstruct an image v.

Part 2.1 Images

Part 2.2 Poisson Blending

The Breakdown

For this part, we want to seamlessly blend an object or texture from a source image into a target image. The simplest method would be to just directly apply the pixels from one image into the other. Unfortunately, this will create very noticeable seams, even if the backgrounds are well-matched. Instead we will look at a method known as poisson blending which retrieves the gradient of the source image and then blends the intensity values of the outer region from the target image to construct a better blend.

Part 2.2 Images