Radically easy to access on brand approved content for distribution and omnichannel performant delivery. AEM Assets Content Hub and Dynamic Media with OpenAPI capabilities is now GA.
when we have uploaded PDF thumbnail rendition is created. Is it possible to set background color for generated thumbnail by customizing Rendetion image processing step or Thumbnail process step?
Not by using OOB CreateThumbnailProcess API but using ImageMagick API. You may've to customize if OOB API version doesn't support the 'background' flag in your existing AEM version. Check ImageMagick API for more details.