Is there a simple way I can achieve this? I seem to be struggling to get a straight answer on this from searching on Google and other forums.
Or is the only option to open my InDesign file and individually convert all my swatches and images to RGB? This would be a real pain for larger documents.
I would do it in Photoshop but I could do with leaving all the text intact and it will be a PDF that people can view online.
If you are exporting the pdf from InDesign, you can do it when you export. First, open your .indd file in InDesign. Go to the file menu and select export. Once you have selected where you want your pdf to be saved, a dialog box entitled Export Adobe PDF should open. On the left hand side, there is a series of menus. Under Output, you can select Color Conversion: Convert to Destination. Set the destination to an RGB option and there you have it. Finally, click export and you should have a pdf in RGB without having to painstakingly alter your original InDesign file.
I wouldn't do this manually I would do it with something like Ghostscript or PDFtk
Ghostscript
gs -sDEVICE=pdfwrite -dBATCH -dNOPAUSE -dCompatibilityLevel=1.4
-dColorConversionStrategy=/sRGB -dProcessColorModel=/DeviceRGB
-dUseCIEColor=true -sOutputFile=output.pdf input.ps
The above was taken from this answer: How to convert PDF from CMYK to RGB, for displaying on iPad?
I dont have Ghosscript installed on my box yet but you could always try the reversal from this:
gswin32c.exe ^
-o c:/path/to/output-cmyk.pdf ^
-sDEVICE=pdfwrite ^
-dUseCIEColor ^
-sProcessColorModel=DeviceCMYK ^
-sColorConversionStrategy=CMYK ^
-sColorConversionStrategyForImages=CMYK ^
input-rgb.pdf
taken from this question: Script (or some other means) to convert RGB to CMYK in PDF?
