In general you're right, but it's actually not quite that simple.
When you read a computer file from a disc, it is often checksummed or validated, so either what you get is perfect or you get an error.
However, the overall HDMI signal is not totally validated.... so, for example, if the signal is weak, you can get a lot of tiny errors.
Those tiny errors may show up as individual pixels, or groups of pixels, that are the wrong color, or just missing.
(The signal is made up of numbers, but if a few bits here and there go missing, you end up with a few
wrong numbers.)
As a result, if you have a weak signal, you can end up with small gaps, or "small sparklies", in the image.
(These are usually the result of a really weak signal... usually from a very long or poor quality cable.)
With something like a cable TV or streamed image, the image itself is transmitted in somewhat large squares, which is why you get that blocky thing going on when you lose signal for a second or two.
Each square block is essentially "either perfect, missing, or garbled".
The "blocky artifact" occurs because one or more of the compressed "picture squares" is flawed, and so "the edges fail to line up perfectly".
(If you look carefully, at different "bad" images, you'll notice different patterns of squares.... that's because different compression algorithms, for example h.264 and HEVC, use different shaped and sized "blocks".)
With HDMI, the same thing can occur at the scale of individual pixels - and a sprinkling of incorrect pixels visually looks like "little sparkles".
It all depends on the underlying system of data transfer.
For example, when you play a CD, the data on the disc is actually processed, verified with checksums, and
CORRECTED if there are errors.
You can
ONLY get the wrong numbers from a CD if the wrong data is read from the disc,
AND two separate levels of digital error correction fails to correct them....
The reason most of those "audiophile tweaks" for CDs are snake oil is simple: the digital error correction on CDs is
VERY effective.
Literally, out of hundreds of CDs, and thousands of songs, I've seen less than a half dozen actual errors.... each lasting a few hundredths of a second.
(When you rip a CD, most modern CD ripping software actually confirms the checksums when you rip the disc, and reports if the rip is anything but perfect.)
Certain other digital transmission methods, like Toslink optical, and HDMI, actually
CAN get data errors because they don't check quite as thoroughly.... although errors are still quite rare.
Someone correct me if I am wrong, but this problem is virtually impossible to have. HDMI passes a digital signal so you either get the video signal or you do not. As long as you get the information all hdmi cables should look the same. Now if you are having an issue with the picture blinking on your tv that may be related to the cable.
I do believe you are correct.
