feBlend filter

parameters:

mode: normal multiply screen darken lighten
in: first picture
in2: second picture

Tool: you can change mode for operation and see result on pictures of your choice

Example of code:

<defs>
<filter id="MyFilter" filterUnits="userSpaceOnUse" x="0" y="0" width="400" height="400">
<feImage xlink:href='#MyImage1' result='pict1'/>
<feImage xlink:href='#MyImage2' result='pict2'/>
<feBlend id='fbl' in='pict1' in2='pict2' mode="screen"/>
</filter>
<image id="MyImage2" width='400' height='400' xlink:href='fondu3.jpg'/>
<image id="MyImage1" width='400' height='400' xlink:href='bateau.jpg'/>
</defs>
<use filter="url(#MyFilter)" x='0' y='0'/>