Scanning photos onto one's hard drive - why are the photos clearerthan the scan

[Patrick Briggs]

Hi,

Does anybody understand why when one scans photos off an Epson 1200
Perfection (not accurate I think) scanner the results are slightly less
sharp than looking at the photo itself.

I scanned at 600 dpi and used Adobe Acrobat 6.0 to process the image
size down to 1100 x 700 pixels. I tried higher dpi setting and allowing
more pixels but it didn't seem to make a difference.

I wonder if it's something to do with older scanner technology (it's a 5
year old scanner at least) or just a reality of scanning photos with
consumer scanners. I assume that $1000 scanners used by ad agencies
don't have this problem.

If this is the wrong group to posts this to, does anybody know of a
newsgroup that would be able to help?

Thanks in advance.

Regards,

Patrick

 

[Bart van der Wolf]

SNIP

I scanned at 600 dpi and used Adobe Acrobat 6.0 to process the image
size down to 1100 x 700 pixels.

Is there any specific reason you used Acrobat for resampling?
Quality resampling requires special attention as to the algorithm
used, and sharpening after resampling.

Also, if you are judging the results on screen, which has only
1/3rd to 1/5th of the resolution of glossy paper prints, you will
certainly see lower sharpness whatever postprocessing you did.

Bart

 

[Bob]

I'm having the same problem with a recently purchased 8400F, which gets
great reviews. The copy frankly is lousy. I can do better by
rephotographing the print with a 3 megapixel camera.

The original photo is a 1.5MB jpg file. The copy is a 225KB file. The
resolution set was 300 dpi. Cranking up the resolution increases file
size and noise, but not sharpness. It is not surprising to me that a
file that small is not sharp, but I have no idea why it's that small.

I'm at a loss.

 

[Ken Weitzel]

Hi,

Does anybody understand why when one scans photos off an Epson 1200
Perfection (not accurate I think) scanner the results are slightly less
sharp than looking at the photo itself.

I scanned at 600 dpi and used Adobe Acrobat 6.0 to process the image
size down to 1100 x 700 pixels. I tried higher dpi setting and allowing
more pixels but it didn't seem to make a difference.

I wonder if it's something to do with older scanner technology (it's a 5
year old scanner at least) or just a reality of scanning photos with
consumer scanners. I assume that $1000 scanners used by ad agencies
don't have this problem.

If this is the wrong group to posts this to, does anybody know of a
newsgroup that would be able to help?

Thanks in advance.

Regards,

Patrick

Hi Patrick...

It's been a while since I had a 1200; now have a 3200 photo, but I
promise you that scanned photos should look wonderful on your screen.
(tiny disclaimer; you can't make a silk purse out of a sow's ear, so
much depends on the quality of the original photo)

I wish I could remember the software that came with the 1200, but
can't. Updates are available free of charge from Epson's site, get
them and install them.

If you have Photoshop or Paint shop pro (or can afford to buy them, then
do so) and use them. If the budget is tight, then download a copy of
Irfanview. Use the scanners twain driver to "automagically" import
the picture into the host software. If (and that's a big if) the
1200 twain driver permits, then use the professional option. Set the
mask to cover only picture (no blank area), and click the auto button.
Next click the histogram button, pull the white down just a bit, and
do your scan.

I think this might give you a better start. Let us know.

Take care.

Ken

 

[Don]

Does anybody understand why when one scans photos off an Epson 1200
Perfection (not accurate I think) scanner the results are slightly less
sharp than looking at the photo itself.

How are you measuring this? What I'm getting at is that if you look at
a 600 dpi scan at full resolution on the screen you see much more
detail then when looking at a photo. In other words, if you look at a
photo with a magnifying glass you'll probably find it not very sharp.

I scanned at 600 dpi and used Adobe Acrobat 6.0 to process the image
size down to 1100 x 700 pixels. I tried higher dpi setting and allowing
more pixels but it didn't seem to make a difference.

Acrobat is geared towards text so it's very likely there is some heavy
so-called "anti-aliasing" going on to "smooth out" jagged lines. What
this does in reality is make everything unsharp and fuzzy so you don't
see the jaggies. :-/ For images this is, of course, fatal. So, try to
turn anti-aliasing off in Acrobat or, better still, use a dedicated
image editor.

I wonder if it's something to do with older scanner technology (it's a 5
year old scanner at least) or just a reality of scanning photos with
consumer scanners. I assume that $1000 scanners used by ad agencies
don't have this problem.

No, the scanner specs are fine. Photographs have only about 300 dpi
resolution anyway. If you made contact prints from large format plates
then maybe 600 dpi. So a 600 dpi scanner is certainly capable of
scanning photos.

If this is the wrong group to posts this to, does anybody know of a
newsgroup that would be able to help?

You're in the right place! ;o) Thanks for asking!

Don.

 

[Bob]

"How are you measuring this? What I'm getting at is that if you look at
a 600 dpi scan at full resolution on the screen you see much more
detail then when looking at a photo. In other words, if you look at a
photo with a magnifying glass you'll probably find it not very sharp."

I'm measuring it by looking at either a full size image in Adobe
Photoshop Elements or a 4X6 print. Either one looks very soft. My
eyes are neither really critical, nor, for that matter, very good.

I copied a test print by photographing it with a 3MP camera, and the
resulting copy was noticeably sharper than the one off the 8400F. Is
that possibly right?

 

[Don]

"How are you measuring this? What I'm getting at is that if you look at
a 600 dpi scan at full resolution on the screen you see much more
detail then when looking at a photo. In other words, if you look at a
photo with a magnifying glass you'll probably find it not very sharp."

I'm measuring it by looking at either a full size image in Adobe
Photoshop Elements or a 4X6 print. Either one looks very soft. My
eyes are neither really critical, nor, for that matter, very good.

The print of a scanned image adds more complications when evaluating
this because the printer driver must process it, etc.

I copied a test print by photographing it with a 3MP camera, and the
resulting copy was noticeably sharper than the one off the 8400F. Is
that possibly right?

It could very well be that the scanner does indeed produce unsharp
scans. However, conventional flatbeds have some depth of field so
that's not very likely, but perhaps (it's an old scanner, you say)
over time the assembly got shifted somehow e.g. if you moved the
scanner, kicked the desk, or whatever. My first couple of scanners
(both flatbed and film) had a "parked" position and before moving
either of them I had to screw the assembly in place after parking.

Also, digicams use a completely different process than scanners.
Without going into too much detail, digicams actually produce much
less sharp images so they always include a sharpening step before
saving. This may account for sharper appearance of a digicam shot.

One last thing. We perceive sharpness as increase in contrast of the
border area between light and dark. That's what these "sharpen"
filters do. They increase the contrast of border areas. The bottom
line is that it's very difficult to asses sharpness based on our
perception alone because our eyes are inaccurate and play tricks.

If you really want to get to the bottom of this you should try some
objective tests like the "slanted edge". Search the archives or google
for the term for more details. In a nutshell a sharp object, usually a
razor, is scanned at an angle. The resulting "pixel staircase" is then
mathematically evaluated to deduce the actual resolution i.e. what the
scanner actually resolved.

Don.