That function does not use any <img> attribute for sizing:
`function printCustomSizedImageMaxHeight($maxheight) {
if (getFullWidth() === getFullHeight() OR getDefaultHeight() > $maxheight) {
printCustomSizedImage(getImageTitle(), null, null, $maxheight, null, null, null, null, null, null);
} else {
printDefaultSizedImage(getImageTitle());
}
}`
It's not really meant for thumbs but for the sized image on image.php as such it works together with the image size you define in the image options.