My question is very simple and straight. I normally take a preview option while scanning a document in my scanner where sometimes I adjust its boundary and reduce the overall size of the document to be scanned.

In the case I am sure I want to scan the complete document without any alterations, will taking the direct scan option without 'preview' option save some electricity? (Since the roller/drum hardware will do only one cycle of scan instead of two).


Panhandel's answer is right, but incomplete.

A final scan can waste more energy, by simply increasing the DPI resolution of the scan. Increasing the resolution can make the roller run at lower speeds. as the tube is constantly lit until the scan ends. Another situation can be that the roller runs twice (I've experienced this somehow with Xerox photocopiers).

On the subject of photocopiers, most of them don't have a display large enough to make previews. Those who do show a very little thumb. I suppose it can be enlarged, but the point is that those instruments usually produce good results, thanks to the circuitry inside.

Regardless of everything, the amount of energy a scan wastes is almost a residue of what the output source (the computer) wastes. (source .pdf, read page 2). In most cases, I need a preview to make sure that certain alterations (increasing contrast, luminosity, gamma adjustments) or that the final size is well adjusted. I have scanned several documents and I only need to preview once, as the rest of the pages can usually follow the settings defined at preview.

To sum it up, a preview is but a very small percentage of the full scan or even the whole process.


Yes it will save power/electricity!

In both scenarios you have to power the roller/drum and light for the same duration for the final scan, but with the preview scan, you are powering the roller/drum and light for additional time.

Obviously, there could be other contributing circumstances that might make you have to re-scan, but in the raw principle, skipping a preview will save power.

For any possible amount of power required by a preview:

Final Scan < Final Scan + Preview

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