I am using export in 'Inkscape' to convert an SVG file to PNG. As I am using a transparent background, the colour of background is automatically set to yellow. I want to change this default colour to white. How can I do this?
At least for documents created directly in Inkscape, File > Export Bitmap... works as expected. If the document has transparent background, the exported PNG becomes transparent. If it was white, then PNG becomes white.
Please check File > Document Properties > Page > Background and check the aplpha channel (A). On RGB tab set all values to 255, including A.
Checked using Inkscape 0.47 on Ubuntu Linux 10.04.
If your problem happens only on convertion of SVG files created elswhere (not in Inkscape), then you need to post that file, so we can try it out.
-b on the command line
E.g. to get a white background instead of the now default transparent:
inkscape -b FFFFFF -h 1024 input.svg -o output.png
Tested on Inkscape 1.0.1, Ubuntu 20.10.
One other method is to create a layer in Inkscape. Choose the layer option in the top menu bar, and create a new layer by choosing "Add layer...". Move that layer to the bottom, by again going to the layer option and choose "move layer to bottom". On the bottom layer, then add a box filled with the background color of your choice.