feDiffuseLighting filter

You have to use light source with feSpotLight, feDistantLight or fePointLight.
You have to use feComposite, feMerge or feBlend to merge picture and light.
feComposite give best result with more parameters.

Parameters:

surfaceScale : height of surface.

diffuseConstant : This can be any non-negative number.

kernelUnitLength : One or two positive numbers. ( space or comma as separator ) 
lighting-color : color value for light
result : name of RGBA raster created

Tool: you can change parameters for feDiffuseLighting, feSpotLight and feComposite ( to merge picture and lightning ) and move with mouse lighting on a JPEG or SVG picture.

Example of code:

<defs>
<filter id="MyFilter" filterUnits="userSpaceOnUse" x="0" y="0" width="400" height="400">
<feImage xlink:href='#MyImage' result='image'/>
<feDiffuseLighting lighting-color='white' result='spot' surfaceScale="1" diffuseConstant="1" kernelUnitLength="1,1"> 
<feSpotLight id='fsp' x='200' y='200' z='200' pointsAtX='200' pointsAtY='100' pointsAtZ='0' specularExponent='16' limitingConeAngle='45' />
</feDiffuseLighting>
<feComposite in='image' in2='spot' operator="arithmetic" k1="0.5" k2="1" k3="1" k4="0"/>
</filter>
<image id="MyImage" width='400' height='400' xlink:href='puzzle.jpg'/>
</defs>
......
<use filter="url(#MyFilter)" x='0' y='0'/>