Run error--Assertion failed

[zxdragon21]

Dear Author.
Thank you for your great work.
I have complied the repo, however, when I run the exe file, an error occured that "Assertion failed: rgba_img.channels() >= 3, file F:\User\zhouxian\ImageStitching\NISwGSP-master\NISwGSP\Feature\ImageData.cpp, line 68".
I have no idea, could you please help me to fix it?

[Sad-Snow]

make sure that your pictures have no less than 3 channels, or convert the mat data to 3 or 4 channels format use opencv api before the line "assert(rgba_img.channels() >= 3);" in ImageData.cpp;