Photo Scanner (DPI question)

I want to make copies of family photos. My idea is to scan them and then print copies.

Does it make a significant difference if I choose a scanner with 1200 dpi vs. 2400 dpi?

Are home printers just as good as photoshop printers?

Photoshop printers? Can’t say I’ve ever heard of that. Most printed material is either 300 or 600dpi depending on the work being done. Beyond 300dpi the quality difference is nearly negligible.

The only reason I can think of for higher resolutions is for enlargement purposes. A scanned image at 600dpi doubles in size when reduced to 300dpi asuming the pixel dimensions are unchanged.

1200 should do you just fine.

Idealy you want to scan at a resolution that provides 300 DPI at the desired print size. So if you scan a 4x5 print, and want to create a new print at the same size, 300 DPI is all you need. Scanning at a higer resolution just creates bigger files, not better prints.

The fun begins when you want to scan a 4x5 and print a 8x10. Now you need to scan the 4x5 at 600 DPI so you end up with 300 DPI at the desired 8x10 size. Scanning negatives and slides require higher resolution because the degree of enlargement is so much greater.

If you have a really soft and fuzzy print to start with, you may never end up with a good enlargement. But if you just want to make same sized copies, the scanner with the lower resolution, and price, will do the job.

Here’s a good website with lots of information:

Epson Photo Stylus printers do an excellant job and can be obtained for less than $100 US. Their more expensive models are a little faster and have some more features, bt the output looks about the same.

If you’re just scanning and printing family snapshots, just about any scanner will do the job, but see if you can try out a few printers, to see which give better color fidelity.

Also, Photoshop is image-editing software, not a type of printer.

I think he meant a printer at a photoshop. Many stores such as Walmart etc. can print from your CD or memory card.

I believe the reference to “photoshop” was about going to a professional shop and have them scan and print the images. For a few shots, that’s what I’d recommend. If you want to do a lot of photographs, it becomes cost-effective to do it yourself.

Definately get a true photoquality printer. The Epsons with “Photo” in the name are great, but Canon and HP also make some very nice photo quality printers. You’ll also need very high quality paper to make the best prints.

If you want really good quality have the negatives scanned professionally as they have a much wider color and luminance range than the paper prints. If you are scanning the prints any scanner will do.

Thanks for your input.

p.s. By photoshop, I did mean a professional photo store.

I have a similar question along these lines, if I may ask it in this thread: I have a lot of 35mm negs I’d like to scan (maybe 100 or 200 images). What is the most cost-effective way to do this at a high resolution (I may enlarge prints to 11 x 17 or more)? Should I buy a good neg scanner (I think about $2000)? Pay a shop to do it (maybe $15 a scan)? Or is it possible to rent a good neg scanner?

Thanks for any help.

I use a Nikon Super Coolscan 4000 for 35mm, and it’s **way **better than my old one (also a Nikon). If you’re planning to enlarge to 11x17, you’ll need image manipulation software (like Photoshop) to tweak the images after they’re scanned. If nothing else they’ll need to be sharpened.

Of course, it depends what you plan to do with the images. If you just want to store them on your computer, or on disks, even 75dpi would be sufficient. Getting to 300dpi or higher only matters if you plan to print the images.

What * GaryM* says is correct. What I usually do is scan the majority of my photos at 300 dpi. If there’s a face shot I like I square in the area and scan the photo at 600-1200.

One thing, if you ever open the pictures in a .jpg viewer (usually for cropping) and then resave them from there, remember that the default on a lot of programs is 80% quality so you want to make sure to move this option back up to 100% if you crop anything.

I once tried to “test” what dpi worked best for printing pictures. The problem (for me) was that the unit of measurement used by my scanner did not match up with the unit of measurement used by my printer. As far as I can tell, it still doesn’t.

Most everyone understands the printer’s units: dpi, which means dots per inch. When I did these “tests,” I was using a LaserJet printer with a top resolution of 600 dpi. Now with photo quality printers, the top resolution is 740 or 1200 dpi. I have found that I get photo-quality prints at 740 dpi, and rarely try to use a printed image at 1200 dpi (the file takes up four size the disk space, so if I can’t see the difference, why bother with the extra disk space (as well as computing power, etc) to deal with these humongous files).

The scanner, however, as well as my image editing program, uses lpi as the unit of measurement: lines per inch. LPI is not the same thing as DPI. So I was trying to find out what LPI matched up with 600 DPI. I printed the same image saved at various LPIs, to see when I noticed there was no improvement.

I forget what my initial unscientific results were; but here is what I go by now:

For any graphic used on a web page: 75 lpi.
For a graphic being printed out at 740 DPI: 150 lpi.

These numbers seem to work well enough for me.

If anyone has a better “scale” to use, by all means let me know.

That being said, I almost always scan images in at 600 lpi. Then I will adjust brightness and contrast, crop, or otherwise edit (remove imperfections, delete a background, etc). After all editing, I usually save a version of the graphic at 300 LPI, just in case it will need future editing or redoing, and then save the final image at 150 or 75 lpi, depending on the intended use.

It is my impression that the higher resolution the image is in, the better and more accurate all editing will be, and 600 is a high enough resolution to more than adequately exceed whatever end result resolution I wind up with. In a few small cases, I will be enlarging an image enough (say more than four times it’s original size) that I will scan using 1200 lpi resolution, but in those cases the image area is usually so small to start out with that it doesn’t take forever to scan or edit the image.

I also save all “original version” and the files I end up using for printing as TIF images, which I believe have no compression and therefore no original information is lost.

Does this jive with everyone’s beliefs and experiences? If not, I wouldn’t mind my opinions being corrected.

Bear in mind if you scan at 1200 dpi your file size per picture is going to be (for an 8 x 10) 1200 x 1200 x 80 =115,200,000 pixels. Which is about 120megs I suppose.

Regarding Bob55’s advice: Each iteration of converting from jpeg and back creates substantial loss in quality. Save the image in a non-lossy format, such as lossless-tiff, do all your image manipulations (crop, gamma, etc.), then save it in jpeg. (But keep the original, back it up on CDR.) The quality numbers in jpeg are not real percentages. 75 is nice enough. If the image doesn’t look good at 75, then the original is bad and needs to be rescanned.

In particular, if the original quality setting was 80, then re-converting and setting it to 100 is worse than a waste of time.