What is Howtek Native Resolution?

[sanking]

In some literature I have for Howtek D4000 and 7500 drum scanners the term "native resolution" is used?

Could someone explain what this means?

Sandy

[Peter De Smidt]

Doesn't this normally refer to non-interpolated resolution?

[fishbulb]

I believe so. If I understand it correctly, native resolutions are all multiples of the scanner's maximum optical resolution. So for the 4500, it would be 4000/2000/1000 DPI.

In the Digital Photo Lab software settings you can turn off interpolated resolutions, I think with the "optical only" setting. This will limit the DPI choices to multiples of the native resolution.

[onnect17]

The scanners control the speed of the drum up to 1200 rpms, 1600 rpms or a percentage of maximum (if speed clamp is used) depending of the model. The dpi does not need to be multiple because it is determined only by the speed of the DC motor (no clock here), but are typically predetermined values. The flexible range, the difference between the slowest and fastest rotation speed, is around 4x, so in terms of dpi let's say 8000-2000, 5000-1250, 4000-1000. Here, the speed of sampling by the ADC should be constant, at the maximum rate.

After that, for lower resolutions, the system is either dividing the clock that sets the pace of the sampling by the ADC or is just simply ignoring samples or doing some averaging.

In any case, the apertures list is the best reference for each of the predetermined/natives resolutions. After all they set the true optical resolution.