The image returned to the client in response to a
req=img request is derived from the composite image by considering the following values:
attribute::MaxPix, and the size of the composite image.
hei= are specified, and
scl= is not, composite image is scaled so that it fits fully within the view rect defined by
hei=. If the aspect ratio of the view rect is different from that of the composite image, then the scaled composite image is aligned within the view rect using the
align= value, if specified, or it is centered otherwise. Any space not covered by image data is filled with
bgc= or, if not specified, with
scl= is specified, the composite image is scaled by that scale factor. If
hei= is specified as well, the scaled image is then cropped to
hei= or extra space is added, as needed.
align= specifies where the image is cropped or extra space is added, and any extra space is filled with
scl= are specified, and if either width or height of the composite image exceeds
attribute::DefaultPix, then the composite image is scaled to not exceed
attribute::DefaultPix. Otherwise, the composite image is used without scaling.
To guarantee that the view image is returned without any further scaling, specify
rgn= is specified, the reply image is then cropped accordingly to arrive at the final reply image size. This size is compared with
attribute::MaxPix (if defined), and an error is generated if the reply image is larger in either dimension.
fmt= specifies data without alpha, any transparent areas in the reply image are filled with