The way we perceive an image is highly dependent on the edges or gradients in the image.
In this paper, we explore an optimization framework for image and video manipulation
that places constraints on both colors and gradients.
Our optimization framework consists of three steps.
First, a set of horizontal and vertical pixel gradients are computed.
Next, the filter determines a set of desired gradients and data values for the filtered image.
These values form a set of constraints on the filtered image.
Unfortunately, there typically does not exist an image that satisfies these constraints.
As a result, approximate solutions must be used that minimizes some energy function.
In our final step, we define an energy function for the constraints.
A set of weights controls the influence of the constraints on the final image.
After performing energy minimization, we find our result.
Using this framework, there are a large number of filters that may be implemented.
For instance, we can sharpen an image.
Here are the horizontal gradients from the original image,
the sharpening function that increases the gradient magnitudes,
and the resulting gradients and filtered image.
An improved sharpening filter may be applied using edge saliency.
An NPR effect can be achieved by removing gradients with less saliency and increasing those with more.
Finally, gradients at specific orientations may be increased to create a pseudo-relighting effect.
Our filters may also be applied to videos.
For images, we define a set of constraints on neighboring pixels.
For videos, we can add temporal constraints between corresponding pixels.
We now show a variety of results using our approach.
Thank you for watching.
Here we show our pseudo-relighting result versus adding a simple intensity ramp to the image.
Pseudo-relighting may also be used to direct attention to or away from a vanishing point.
Thank you for watching.
Pseudo-relighting may also be used to direct attention to or away from a vanishing point.
Pseudo-relighting may also be used to direct attention to a vanishing point.
Pseudo-relighting may also be used to direct attention to a vanishing point.
