Changing the default portfolio gallery image size
The default image size for the Portfolio Gallery Template in the Dandelion theme is declared in the functions/portfolio.php file, starting on line 68:
Two column layout:
$pexetoImageSizes[2]=array('width'=>427,'height'=>230);
Three column layout:
$pexetoImageSizes[3]=array('width'=>272,'height'=>183);
Four column layout:
$pexetoImageSizes[4]=array('width'=>195,'height'=>130);
If you would like to modify the default size, just change the width/height value for the relevant column layout.