There was a channel that broadcast a color bar target periodically but it was a complete waste of time. All it did was calibrate you to that channel... none of the other channels matched exactly (some may have been close, others not so much). Furthermore, every PROGRAM is different so even if you calibrate to one channel, every time they change programs, you might need some fine tuning. So what's the point?
Furthermore, digital video has more or less eliminated variations... the cable box would have to intelligently process the video to CHANGE it. The video data is 1s and 0s that can't be "good" or "bad" they can only be 1 or 0. There is no 1.0007 or .0098... you have either nothing (loss of video) or a combination of 1s and 0s. If the combination of 1s and 0s is not precise, you also lose the video completely since the ORDER of the 1s and 0s has to be very precise.... move them just one "slot" forward or back (in time) and you're likely to lose video altogether. All the box does is transmit the 1s and 0s that it receives from Velocity, CNN, or ABC. The only processing the box does is perhaps to convert 480 to 1080 or 720 to 1080, etc. and that might be messed up... but if your box sends whatever it receives, there's really no point in "calibrating the box" that's just an old concept from the analog video days that really no longer applies. Bottom line... you have 200+ channels running 2000+ shows every day and all of them are just a little different from each other. You can't stop it and you can't compensate for it.