Markdeep currently has a bug where the line
*bptr = static_cast<unsigned char>(*fptr * 256.0);
is rendered as
*bptr = static_cast<unsigned char="">(*fptr * 256.0);
As a workaround, we use
*bptr = static_cast< unsigned char >(*fptr * 256.0);
This is in the file rtw_stb_image.h. Once this bug is fixed in Markdeep, remove the extraneous spaces inside the angle brackets.