If your Express Server is outputting scenes that appear blurry there are several things you can do to try to correct the problem.
Catalog groups nested inside other catalog groups can sometimes be blurry. If you have blurry images in nested catalog groups, try reorganizing the catalogs so that no catalog group contains another catalog group.
Flatten catalog groups by removing catalog groups from inside catalog groups in the Express Server Manager (see Editing a Catalog Group).
For more information about catalog groups, see Adding and Configuring Catalog Groups.
NOTE: Catalog groups are referred to in the catalogs.xml file as "multicatalogs".
Express Server can be configured to use one of three algorithms when interpolating pixels during reprojection and when scaling a scene to the requested output dimensions . If your images are blurry and your resampling algorithms are set to "nearest neighbor" interpolation, try specifying "bilinear", and if they are already set to bilinear, then push them to "bicubic". Bicubic interpolation results in the highest image quality but is the most CPU intensive.
For more information see Setting Basic Express Server Settings.
In cases where MrSID or JPEG 2000 pixel data must be scaled up or down because the resolution of the requested scene falls between two zoom levels, Express Server has a default bias toward scaling up from lower resolution data and favoring performance over image quality. For better image quality, try decreasing the value of this bias or eliminating it altogether.
For more information see Setting Basic Express Server Settings.
If it's possible to set up your catalogs in such a way that your images are being reprojected as seldom as possible you'll have clearer results. We recommend making sure that your data is in the coordinate reference system that your end users most often work in.