Smoothing the intensities Intensity Smoothing More Smoothing

Intensity Derivative Smoothed Intensity First Derivative Second Derivative

The Derivative of a Convolution

Analyzing a 2D image Image after smoothing and second derivative Image Black = Negative White = Positive Zero-Crossings

Smoothing a 2D Image To smooth an image, I(x,y), we can convolve with a 2D Gaussian:

Differentiation in 2D To differentiate the smoothed 2D image, we will use the Laplacian operator: We can again combine the smoothing and derivative operations: (displayed with sign reversed)

Detecting intensity changes at multiple scales

Computing the contrast of intensity changes

The Eye

The Neuron Major parts of a neuron: Cell body Axon Terminal Synaptic cleft Dendrites

Projection from the Retina

Retinal Ganglion Cells Retinal Ganglion cells have receptive fields that exhibit a center-surround structure.