In NPrinting reports, a max image width/height parameter that should be 3000 x 3000 by default. If the user wants to add one extra long image, the generated image could be either cut off or have lower image quality after settings a large value in "Data displayed width" and "Max Width" in Image properties.
Environment:
Qlik NPrinting
Cause:
All Sense images are rendered by NPrinting or better RWR (not by Sense) using an embedded browser, to render a chart of 200px X 100px NPrinting has to render it to higher values:
1) Normal -> image rendered at 200px X 100px @ 96 dpi;
2) High -> image rendered at 400px X 200px @192 dpi;
3) Very high -> image rendered at 800px x 400px @ 384 dpi.
All these images are then reduced using chromium zoom so that the chart actually fits the desired output size of 200px X 100px.
Resolution:
On C:\Program Files\NPrintingServer\NPrinting\Engine\engine.config file, there are two parameters:
<!-- max image dimensions rendered supported by CEF, the final image is upscaled to produce the correct dimensions -->
<!--
<add key="webrenderer-max-image-width-px" value="3000" />
<add key="webrenderer-max-image-height-px" value="3000" />
-->
These define the max image rendering dimension performed by the Chromium Web Browser embedded in the WebRenderer component used by NPrinting.
If the rendering size exceeds what imposed by the engine parameter wrote above (3000 x 3000 by default), it is rendered at the maximum permitted value a(keeping aspect ratio) and then up scaled (with loss of image quality).
So if you have an output size of 4500 x 2500 to have the best quality you should set in the engine.config file max-rendering parameters at least:
1) if you are using "Normal" quality -> 4500 and 2500;
2) if you are using "High" quality -> 9000 and 5000;
3) if you are using "Very high" quality -> 18000 and 10000.
Change "Data displayed width" and "Max Width" to 4500 in Image property
