With Spectrum Viewer you can re-create data that is only available in a hard copy or in a screen shot.
If you only have a hard copy, scan the hardcopy with a scanner, then copy the image to the clipboard. If the data is available in a PDF file or similar, display the graph as large as possible on your screen and then make a screenshot to the clipboard using the keys <alt> + <printscreen>.
Load the clipboard bitmap into SV. Set the bitmap range using the rectangle. Now draw a new data set by clicking on the graph. Finally, if you want to compare the data with another data set, you can resample the new data to match the exact X values of your other data set with the resample to source command.