The image returned to the client in response to a req=tmb request is derived from the composite image by considering the following values: wid=, hei=, attribute::DefaultThumbPix, and attribute::MaxPix.
wid=or the width value of
attribute::DefaultThumbPixfor the width of the view rect. Use
hei=or the height value of
attribute::DefaultThumbPixfor the height. The view rect must be fully specified in this step. (Note that the view rect is the same as the layer 0 rect, if no
size=is specified for layer 0).
catalog::ThumbType=Crop, then the composite is scaled to the smallest image possible while still filling the entire view rect; extra image data is cropped off. If
catalog::ThumbType= Fit, then the composite is scaled to the largest image possible while still fitting the entire composite into the view rect. If
catalog::ThumbType=Texture, the composite is not scaled at all to preserve the resolution specified in
bgc=color (or, if not specified, with
attribute::ThumbBkgColor). The scaled composite is aligned with the view rect using attribute::
ThumbVertAlign. The scaled composite is then merged with the filled view rect without further scaling. Any areas of the composite that extend beyond the view rect are cropped off.