scanning in 600dpi blurrier than 300dpi?

[spincut]

So I was scanning a bunch of older photo's, and I of course just selected the highest DPI on my Canon MG6120.

However, I noticed some photo's looked soft or fuzzy. On a few I tried the 300dpi setting, and even though the resolution is lower and the size is smaller for the picture, it seems as if they are a tad sharper (although maybe they are otherwise not as quality??).

Anyway, I was just curious why that was.

 

[cortexodus]

When you say "blurrier" I wonder the following:

What file format are you scanning to?
What application are you viewing the finished scans with?
Are you viewing those scans at the same zoom levels with that application?

 

[spincut]

JPEG, the basic microsoft image viewing thing (also tried the scan program too). and yes they are equally zoomed.

 

[MN Scout]

Old printed photos don't necessarily have that much detail in them. The 600 dpi photo at 100% magnification will most likely look blurrier than the 300dpi at 100%. The lenses in some scanners are also just not good enough. I didn't look up your scanner, but with some scanning software the maximum resolution is just an interpolated resolution (software resized) so it is still scanning at 300dpi and making up the other pixels.

How do the photos look if you take the 600dpi file and resize it down to half the dimensions? Often this trick of scanning at 600 and resizing to 300 will yield a bit more detail and sharpness than scanning just at 300. IE you have a resolution of 4000x3000 and you resize it to 2000x1500. If you do this I'd suggest saving the 600dpi file in TIFF, then resize and edit, then save out as jpg at the last step. I've done this with good success and yields better results. I'd also be comfortable just scanning at 300dpi and forgoing the hassle - as long as the picture doesn't need editing.

Also make sure that your jpg saving settings isn't at a high compression.

 

[spincut]

Old printed photos don't necessarily have that much detail in them. The 600 dpi photo at 100% magnification will most likely look blurrier than the 300dpi at 100%. The lenses in some scanners are also just not good enough. I didn't look up your scanner, but with some scanning software the maximum resolution is just an interpolated resolution (software resized) so it is still scanning at 300dpi and making up the other pixels.

How do the photos look if you take the 600dpi file and resize it down to half the dimensions? Often this trick of scanning at 600 and resizing to 300 will yield a bit more detail and sharpness than scanning just at 300. IE you have a resolution of 4000x3000 and you resize it to 2000x1500. If you do this I'd suggest saving the 600dpi file in TIFF, then resize and edit, then save out as jpg at the last step. I've done this with good success and yields better results. I'd also be comfortable just scanning at 300dpi and forgoing the hassle - as long as the picture doesn't need editing.

Also make sure that your jpg saving settings isn't at a high compression.

Well the scanner doesnt seem to have a compression setting, so I think that's probably fine.

But the general gist otherwise of what you're saying is that 600dpi isn't actually worse, just something to do with the zoomage of the photo preview? Because, yeah, considering I'm halfway through, I just don't want to have to scan them again .

 

[MN Scout]

The issue is that the original photo printer didn't print at 600dpi. Look really close at the photo infront of you and you'll see that the details are probably soft and don't have crisp defined edges on details like we are used to on digital photos viewed on our monitor. This isn't an issue of digital vs analog, but that the photo labs we used to take film to didn't always take tons of time to make sure the prints were coming out razor sharp (type of paper they print on also makes a difference).

See incoming PM for offer to take a look at an image.

Edit: Put another way. Your photos at 600dpi should be fine. They just may be taking up more space than necessary due to the fact that there isn't 600dpi worth of information to capture off the print, but more around 300dpi of detail. 600dpi scanning is a lot really, but should capture every little detail there is off that paper and make future reprints of higher quality. Here is a nice article http://www.digitalmemoriesonline.net/scan/scan_processing/prints_vs_film_scanning.htm

 

[spincut]

The issue is that the original photo printer didn't print at 600dpi. Look really close at the photo infront of you and you'll see that the details are probably soft and don't have crisp defined edges on details like we are used to on digital photos viewed on our monitor. This isn't an issue of digital vs analog, but that the photo labs we used to take film to didn't always take tons of time to make sure the prints were coming out razor sharp (type of paper they print on also makes a difference).

See incoming PM for offer to take a look at an image.

Edit: Put another way. Your photos at 600dpi should be fine. They just may be taking up more space than necessary due to the fact that there isn't 600dpi worth of information to capture off the print, but more around 300dpi of detail. 600dpi scanning is a lot really, but should capture every little detail there is off that paper and make future reprints of higher quality. Here is a nice article http://www.digitalmemoriesonline.net/scan/scan_processing/prints_vs_film_scanning.htm

Wait....but I haven't "printed" any photo's....this is all about how they look after they have been scanned...not after they have been scanned and printed.

 

[MN Scout]

Yeah I understand you haven't printed anything. Just wanted to point out another benefit of the 600dpi scans you made.

 

[spincut]

Yeah but you said the problem was with the original photo printer. I picked 600dpi for no other reason than it was the highest scan setting and I didn't think there was any downside....but even with your explanation I am still not sure. I mean, I would like to upload these on facebook, for instance, and not have them look worse or blurrier than if I did them at 300dpi...

 

[MN Scout]

The nuances of resizing pictures so they look good on the screen in frustrating to say the least. Not all programs do it optimally. The Windows Picture and Fax Viewer is annoying because it doesn't tell you how far zoomed in you are, so it is difficult to match photos at 50% or 100% levels, and also difficult to make sure you aren't at an odd zoom. In Windows 7, Microsoft Paint will let you choose 50% and 100%, so you could match it up in there to make your decision. The old Microsoft Paint will show it to you at 100%, can remember if you can choose other zooms.

At 50% the program should be showing every other pixel. At 100% every pixel on the screen should be shown once. Now when you go to 200%, should the program show every pixel twice(drawing program), or should it do a smart resize and fix the blocky pixelized look(photo viewing programs). Now when you choose 75%, only 75% of a pixel is supposed to be showing, and we know that doesn't work out, so details go missing and things often look softer, leading us to have to use some sharpening to bring them back out.

When you upload to facebook it will shrink the picture dimensions, then apply output sharpening to the picture to counteract the shrinking. It will do this automatically with all sizes of photos, and it is a good thing. Any time a digital file is shrunk there should always be some output sharpening applied to bring the details back out.

Your scan software will also be applying some sharpening after the scan. With the combination of your photos, 300 dpi, and the scanners default sharpening algorithm may just be coming together to look better.

It is interesting that you say the highest scan DPI is 600. The product page is showing 4800. This would say to me that the optical qualities of the scanner wouldn't be inhibiting a good scan.

 

[MN Scout]

Well Spincut this post is probably way more then you want, but I've been meaning to blog about this, and figured I'd post it here first. I've been doing a bunch of scanning myself, so it is always good to do a bit more research on this topic of sharp scans.

Sharpening Example - Picture of my family's Christmas tree in 2002.

I scanned the photo in Epson Scan at 300dpi and 600dpi. I turned off additional sharpening and it's auto contrast enhancement so I could get closer to what the photo really looks like. I turned the sharpening off because I didn't want it to influence these examples, though I think the program still does some very minor sharpening even when I tell it not to.

300dpi file ended up with the dimensions of 1174x2078.
600dpi file ended up with the dimensions of 2348x4156.

Let's look at the scans in Windows Picture Viewer on Windows 7 so that they are the same size. This is a good example of how bad picture viewing applications can make your photos look.
300dpi - Equate to 38%, 600dpi - 19%

They look pretty much the same here. The pine needles are blurry and the edges of the wrapping paper prints is not defined.

Let's look at 100% crop from the scan to see how much detail was picked up from the start. There is no sharpening added to these pictures after the scan.
300dpi, 600dpi

The 300dpi scan is smaller than the 600dpi scan. The edges in the 300dpi look a bit sharper on the Santa ornament and on the pine needles. The 600dpi scan things are bigger but look a bit soft in general, and no extra information looks to be captured.

What happens if I resize the 600dpi crop to the same size of the 300dpi crop? It'll look a bit sharper. 300dpi crop on left, 600 dpi resized 50% on right.

In the 600dpi picture on the right the pine needles on the branches have more definition, and the edges on the Santa and candy cane are sharper. The 600dpi resize used every other pixel in the file, because I resized it in half using the Nearest Neighbor option in Photoshop. Once resized down the 600 dpi scan does appear to have captured a bit of extra information - we just have to process it to show it. This is one area where scanning it at twice the resolution then resizing later is a benefit.

When the picture is resized to output to the web, send in an email, or to just fit on your screen, it is best to apply some output sharpening. The output sharpening will fix up that blurry look we saw in the Windows Picture Viewer example. Websites like Facebook will apply this output sharpening automatically when you upload the full resolution pictures. There are a few methods that one can use if you need to do this yourself.

Method 0 no control using Photoshop.

• Use File->Save for Web. Choose your desired dimensions, and your sharpening method. Bicubic will appear sharper, and bilinear smoother when resized smaller. Check the box to Convert to sRGB, and embed the color profile.

Method 1 using an Unsharp Mask in Gimp or Photoshop. This is a 1 step sharpening which does not yield as good of results as Method 2. I used to use this myself, but after seeing the better results using Photoshops Smart Sharpen filter I won't be using it.

1. Resize the photo to desired resolution. I used nearest neighbor on my Christmas tree photo with good results.
2. Apply an Unsharp Mask filter. The radius controls the width of the sharpenning on the edges. In Photoshop, Filter->Unsharp Mask. An amount around 30, and Radius of 3 was as good as I good get.

Method 2 in Photoshop, I originally found it on Juza Nature Photography, This is a 2 step sharpening routine, but yields a good resize when the Smart Sharpen filter is applied just once.

1. Resize the photo to 2x the desired resolution using Image->Image Size. Use a sampling method of Bicubic Sharper.
2. Apply a Smart Sharpen filter by choosing Filter->Sharpen->Smart Sharpen. On this 2x image choose an amount between 150-200%, Radius of .2->.3, Remove "Lens Blur", More Accurate.
3. Resize the photo now to the desired resolution. Using Image->Image Size. Use a sampling method of Nearest Neighbor.
4. Apply a final Smart Sharpen filter. Use an amount between 50-100%, Radius of .1, Remove "Lens Blur", More Accurate.

Using Method 2 I was able to come up with this:
Viewed in Windows Photo Viewer at a webish resolution, My sharpened version using Method 2.

The right side is a good example of what the original photo looked like. Maybe even better.