My text books on the subject speak clearly about quantization error, so I reject KMD's claim to the contrary. Maybe the problem has to do with glancing at pictures instead of reading the text and equations?
The quantization grid is not caused by sampling it is caused by the interaction of quantization levels with sampling points. It may not be perceptable but there is no doubt that a waveform created from a digital file must be formed from a selection of points that are selected from a finite number of pre- determined regularly spaced co-ordinates. The digital file is formed from regularly spaced sampling points and reguarly spaced quantization levels therefore the waveform derived from it must have a coresponding regularity.
I work more in commercial TV where video has been digitized since the mid '70s. If what you're describing existed you would not be able to to display diagonal lines, particularly nearly vertical ones. I assure that is not the case.
Actually, images and video resist the use of "ideal" filters, so aliasing is quite common. Those diagonal lines are often quite "steppy".
Quote from: 2Bdecided on 23 March, 2012, 05:22:45 AMActually, images and video resist the use of "ideal" filters, so aliasing is quite common. Those diagonal lines are often quite "steppy".Surely that is because most visual output devices have the same or lower resolution than/as the input signal?
Lesser problems these days for still images, because the lens itself often acts as a low pass filter for the x-mega-pixel sensor.
Quote from: 2Bdecided on 23 March, 2012, 09:38:22 AMLesser problems these days for still images, because the lens itself often acts as a low pass filter for the x-mega-pixel sensor. you mean the lens on the sensor within the chip or the main lens? I think there are filters within the sensor. I have a vague recollection in my head, but I cannot remember what does filters and lenses do on the sensor.