This data adds a lot of size to the files, hence we use the PNG format to keep file size to a minimum. This gives excellent rendering as the slightly blurred backdrop of hillshading at scaling between roughly A5 to A3 on our physical maps.
The hillshading PNG is embedded into the Illustrator and SVG files and you can simply turn the layer on and off like any other layer. It is also possible to make some basic edits to the colour and opacity of the embedded hillshading layer within Illustrator and some other programs.
Advanced editing of the hillshading layer
The separate PNG (or TIFF if provided) file for hillshading that is included with your download is useful if you want to make advanced changes.
To edit the hillshading colours, we recommend you open the file in Photoshop or another pixel-editing application and use colour adjustment layers.
You would then save the edited file and replace the existing embedded layer either in the Illustrator or SVG file. In Illustrator, for example, you could use the relink panel to navigate to your updated hillshading file.
If you are intending to reproduce the map at a large scale, you may want to resample the hillshading file in Photoshop, to scale it up. (We recommend the method of bicubic smoother for upscaling. ) Please note our recommended maximum scaling limits, as the hillshading layer will start to look pixellated if it goes much beyond the recommendation, especially if being used for print work at 300dpi.
Note: some older printers cannot handle the transparent outer canvas of the hillshading layer. If you have technical difficulties with the transparency in the hillshading layer, we recommend you add a sea blue (or other colour) layer to the file and flatten it before replacing it in the vector file.
These advanced editing methods require a moderate level of skill in Photoshop and Illustrator/Corel etc.