Question about scan settings for customers?

[dkf10425]

I have a question about what scan setting instructions do you tell people who email/upload photos to you? Should they scan at 300, 600, or 1200 ppi? I asked someone yesterday to send me a 1200 ppi scan but they emailed me back saying their scanner was only rated at 600 and anything larger it would resample the image. This person was a photographer who has some experience with scanning so they brought it to my attention. However most customers are not knowledgeable about scanners settings/software so my question is what setting should I tell people to scan the photos on before they upload? I don't want to get an image that has been resampled by the scanner, and I don't want to make the procedure too complicated for the person that is getting their photos restored. Many people don't want to mail a precious family photo so I have no choice but to allow people to upload photos to me.

[Stephen A]

Re: Question about scan settings for customers?

Personally, I use 300PPI whenever I'm reprinting - because AFAIK our printer setup is default 300DPI. If I'm going larger, I'll just ballpark my figures and go with a accordingly higher PPI scan.

I guess you could also use a lower PPI scan if you're printing it smaller than the original.

[mistermonday]

Re: Question about scan settings for customers?

Scan resolution is really dependent on what size the ultimate print will be.
Examples: Lets say you have a 4 x 6 inch photo which you want to scan so that you can color correct it and then print is at your favorite Costco lab at 8 x 12 inches. Print quality is considered 300 PPI. So in this case to print 8 x 12 you need 8 x 300 = 2400 pixels BY 12 x 300 = 3600 pixels.
With a 4 x 6 original you will need to scan at 2400/4 = 600 ppi (same as 3600/6). Or another way of expressing it would be 300 times (Output Size Divided by Orig size) in pixels per inch. If you had a 35 mm negative that you wanted to print at 8 x 12 your scan resolution would be 8"/1" x 300 = 2400 ppi (same as 12/1.5 x 300).
If the number does not work out to a std value use the next size up because you can always throw away pixel data if you have a little too much.
Regards, Murray

[dkf10425]

Re: Question about scan settings for customers?

Thanks for both your replies. What I am asking is if a customer wants an enlargement that would require a 1200ppi scan should I let them do it and take a chance on their scanning software resampling the image? Their scanner may not be rated at 1200. Or should I play it safe and just have them scan at 300ppi, then use Fractals to blow up the image? Most scanning software resamples images poorly.

[mistermonday]

Re: Question about scan settings for customers?

I have a couple of old scanners from 1998 in my "retired hardware" pile. They werre 2400 dpi optical scanning resolution. During that era, even the cheapest low end scanner was capable of 1200 dpi. So unless the customer has a real dinosaur, let them scan at 1200. Upsizing from 300 dpi, even using GF, is not as good as scanning at 1200 unless you are certain that the scan has already been upsampled.
Regards, Murray

[Stephen A]

Re: Question about scan settings for customers?

Thanks for both your replies. What I am asking is if a customer wants an enlargement that would require a 1200ppi scan should I let them do it and take a chance on their scanning software resampling the image? Their scanner may not be rated at 1200. Or should I play it safe and just have them scan at 300ppi, then use Fractals to blow up the image? Most scanning software resamples images poorly.

If they can't get access to something that scans above 300DPI tell them to have a shop scan it for them at 1200DPI (if that's what you need).

I guess? Best advice I can think of for that... Although I don't really know how you would get a 1200DPI image through email unless you're providing them with a FTP.

[duwayne]

Re: Question about scan settings for customers?

Something else to consider besides resolution is the dynamic range of the scanner. If they are using a generic document scanner, a lot of detail in the shadows and highlights will be lost. For best results, have the image scanned at a photo processing shop (camera or print shop) on a photo scanner with a Dmax greater then 4.0 . It's only a few dollars but can make a difference.

Another concern is the file format. You should ask for a TIFF file if possible or worst case JPEG with the lowest compression setting. TIFF file will be very large and most likely will require that they mail you a CD. Many e-mail services will block large file.

[dkf10425]

Re: Question about scan settings for customers?

I have a couple of old scanners from 1998 in my "retired hardware" pile. They werre 2400 dpi optical scanning resolution. During that era, even the cheapest low end scanner was capable of 1200 dpi. So unless the customer has a real dinosaur, let them scan at 1200. Upsizing from 300 dpi, even using GF, is not as good as scanning at 1200 unless you are certain that the scan has already been upsampled.
Regards, Murray

This last customer told me his scanner won't go above 600ppi. I guess he really has an old scanner or is wrong.

If they can't get access to something that scans above 300DPI tell them to have a shop scan it for them at 1200DPI (if that's what you need).

I guess? Best advice I can think of for that... Although I don't really know how you would get a 1200DPI image through email unless you're providing them with a FTP.

Thanks! I have a site. Configured to allow 100MB uploads.

Something else to consider besides resolution is the dynamic range of the scanner. If they are using a generic document scanner, a lot of detail in the shadows and highlights will be lost. For best results, have the image scanned at a photo processing shop (camera or print shop) on a photo scanner with a Dmax greater then 4.0 . It's only a few dollars but can make a difference.

Another concern is the file format. You should ask for a TIFF file if possible or worst case JPEG with the lowest compression setting. TIFF file will be very large and most likely will require that they mail you a CD. Many e-mail services will block large file.

Thanks! Yes, for those people with generic document scanners, getting the photo scanned at a print shop would be optimal. And about the large TIFF file I have a site that allows for large uploads. I shouldn't have mentioned email as it didn't apply to me.
Another question. How come you guys are using the term DPI as opposed to PPI? My photoshop calls it PPI. My scanner calls it PPI. I thought DPI was the print output?

[dkf10425]

Re: Question about scan settings for customers?

That last question I asked about the ppi/dpi terms, I did a little research and this is what I found out.
"PPI seems to be an Adobe invention designed to distinguish between the single colour dots of ink jet printers and offset press, measured in DPI, and the multicoloured pixels of a digital image, measured in PPI. It might have clarified things had it come earlier but it came too late and has done nothing to clarify and perhaps a little to obfuscate.

For all practical purpose you can treat them as identical."

So now I know why some sites refer to it as dpi, some ppi.