Trying to use the Djatoka jpeg2000 image viewer to display the image tiles / regions served up by an installation of the now-defunct eRez image server underscored the value of a good web API.
eRez Tile API
| Parm Name | Type | Function |
|---|---|---|
| src | string | path to the ptif src, relative to the eRez image root |
| width | integer | width of the resulting image tile (will stretch to fit) |
| height | integer | height of the resulting image tile (will stretch to fit) |
| top | float | the position of the top edge of the tile relative to the entire scaled image, expressed as a decimal fraction |
| left | float | see "top" |
| bottom | float | see "top" |
| right | float | see "top" |
| scale | float | the ratio of the dimensions of an entire image composed of tiles in the requested size to the dimensions of the original image, expressed as a decimal fraction. |
| tmp | string constant | the value is "ajax-viewer", unquoted |
OpenURL getRegion API
| Parm Name | Type | Function |
|---|---|---|
| svc.level | integer | a scaling indicator, as specified here |
| svc.region | integer or float list | the top edge position, left edge position, region height and width. Concatenated as a comma-delimited value. |
| svc.scale | integer or float list | scaling factor as either a single value, or a targeted width and height. If the latter, a value of zero for one of the dimensions indicates the original proportions should be maintained. |
Translating OpenURL Level to eRez Scale
After calculating the maximum levels, any given level converts to scale as:
scale = 1 / 2(maxLevels - requestedLevel)
