Scanning Stamps At High Res

Before posting this question I searched 18 pages of search results but did not see any reference to the topic below.

I noticed a very recent post where 4800 dpi scanning was used for a stamp. I recall reading in an old yahoo group that scanning 600 dpi or high can potentially cause damage to a stamp due to intense light. The higher the resolution, the slower the scanner head moves under the stamp so it follows that the higher the resolution, the greater the exposure of the stamp to very intense light.

What do the chemists, physicists, and materials scientists in the forum think about this?

If 4800dpi was an issue to damage stamp print I would of heard about it by now I recon.

If the light generated by scanning at such a DPI was like hours or more like months of exposure would be needed to damage stamp printed.

Time is the factor here. It will be interesting to hear what others think on this.

An old wife's tale, I'm afraid. It's UV light that does the damage to any colours, especially those at the red end of the visible spectrum (look at an old red car, for example, and see the damage that exposure to sunlight does; the search for a truly colour-fast red is still going on after decades).

The glass on the scanner would be sufficient to act as a filter for even the most intense of UV light for the duration of exposure required for a high resolution scan. However, the light generated by the scanner has pretty much zero UV, so you have nothing to worry about.

The only thing I would worry about is "what to do while the scanner is scanning at such high resolution?"

Hope this helps :-)

Here's a thought: experiment. Take a common old & inexpensive stamp and scan it at 4800dpi and see what happens.

Basically scanning at such a high resolution only creates an enormous file. 1200 dpi should be more than adequate. Also, another option is scanning at 600 dpi at 200%. That should bring out any details.

Iknow my monitor is not capable of seeing the difference and if they are printed out the photo paper is only capable of so much resolution.

Simply put something non-transparent between the stamp and the scanner glass, thereby protecting the stamp.

You know, I can't keep doing this for you...



-IBFS

Very useful and valuable info. I'd never go higher than 1,200 dpi and that would be rarely. 300 is quite adequate for most situations. Thanks for the reassurance.

I would like to be shown sometime how these big scans are so superior. The pictures that we post on the site for the most part are fine with me.

But many of these SCF-posted scans would have been optimized to reduce file size - in The Bad Old Days, down to under 100K - so much (but not necessarily all) of the advantage of higher resolution might have been lost.

Posted herewith are 200 & 2400 dpi scans of the same piece, treated as identically as I can easily manage; scanned, cropped, rotated, and optimized.

To maximize advantage to the low-res scan, the 2400 dpi scan was 'optimized' to the size (300*550) of the as-cropped 200 dpi scan. The 'quality' was left at the default (80/100) and, in contrary to my usual practice, the sharpening was left at its defualt (0).

I would put incremental damage from higher resolution scanning at the bottom of my risk list, but that's me.

Cheers,

/s/ ikeyPikey

Be careful. Depending on the scanning software, scanning 600dpi at 200% may NOT be the same as scanning at 1200 dpi. The latter method will be a true native resolution scan (assuming the scanner's native resolution is 1200dpi or higher), but the former could be optically scanned at 600dpi and then digitally interpolated to 1200dpi, which is NOT the same. You want to avoid digital interpolation where possible.

As far as the statement made above that 1200dpi is more than adequate, that isn't necessarily true depending on your purpose.

My regular scanning resolution for my website is 800dpi. However, for plate varieties and capturing blue threads on silk papers, I routinely go above 1200dpi, to either 1600 or 3200 dpi.

A problem though, is that flatbed scanners, even though they may have specs claiming 4000dpi or higher, get blurrier and blurrier as you approach that limit. If color accuracy is not essential, it may behoove you to use a USB microscope to capture tiny details. I use this method to exhibit silk threads in high resolution, as shown below. The main image is from my flatbed scanner, but the inset of the thread was captured using my USB microscope.

While the light is somewhat intence and while the scanner does slow down for higher resolution scans, the total amount of light that is delivered to the stamp is very small. You would have to scan the stamp many many times to ewven begin to affect the color.

As for the idea that glass will completely eliminate color fading - complete baloney. Place a multi-colored stamp on the dashboard of your car and eventually you will see fading (especially yellows and reds). Either the glass is letting some of the UV through, or visible light can also cause fading.

You can see plenty at 600, anymore is a bit overkill

What happens if you try to print a photograph of a 1200 DPI scan. Are you suggesting that the photo paper is capable of reproducing it? Doing the math that would translate into 1.4 million dots which a printer head can't do and the paper can't show.

I have quite a collection of varieties on the Transportation Series of coil stamps. One of the things that a higher scan DPI will bring out is the part of plate cracks that are invisible to the (old) naked eye. Another type of variety is the LOM. Some stamps have very faint guide lines that will not be very visible at 600 DPI, but jump out at you at higher resolutions. There is definitely a use for higher DPI's as well as USB microscopes!

Peter

I agree Peter but will this information show on a photo print?