OldSchool-WI Loc: Brandon, Wisconsin 53919

In answer to---How many pixels in a dot.----------Any number.-----------(So---I answered the question which you claim is in six words----in two?--------------ew

burkphoto Loc: High Point, NC

in the lab biz, we used 250 PPI @ 8x10 as a standard resolution. That referred to 250 original, uninterpolated pixels (or more) coming from an in-camera JPEG or raw file converted to JPEG. Most labs do something similar, using 240 PPI @ 8x10 or 300 PPI @ 8x10 as the basis for their images. We scaled EVERYTHING to that minimum on the server. The printing software did the rest. We used 250 from-the-camera or from-the-customer's converted file pixels per inch at 8x10 as the base.

I should have clarified that earlier. There is no set number of dots in a pixel. Neither is there a set number of pixels in a dot. It just depends... on the situation.

CHG_CANON Loc: the Windy City

Exactly. And that's the point for printing.

For scanning, it's the target pixel resolution. You don't say 'scan to x number of dots', even is the software includes a nonsense dpi field. Rather, you say the target pixel resolution and that is the file generated.

OldSchool-WI Loc: Brandon, Wisconsin 53919

So---(Canon), Did (Burkphoto) answer your question in his easily understood response?------ew

burkphoto Loc: High Point, NC

Different software uses the EXIF dpi headers (X-res, Y-res, X-dimension, Y-dimension... naming conventions vary slightly) differently. Originally, they were there in the age of scanners, to tell page layout software what to do when placing or importing a file onto a layout. The software would read the dpi value and spread the pixels over whatever size that made at that dpi. PageMaker did that. Other software used "bounding boxes" to restrain an image automatically to a given area. If you placed an image in a bounding box, it would expand it to whatever dpi it could, perhaps giving you a warning if the resolution would be too low.

If you imported a 4"x5" 72 dpi image from a scanner into PageMaker, it would flow onto the page as a 4"x5", low resolution "for positioning only" (FPO) placeholder. Computers were slow, so FPO images were used to speed the design process, as computers could handle small files much faster.

If you placed a 1200 pixel by 1500 pixel 72 dpi image from a scanner into PageMaker, it would flow onto the page as a 16.67" by 20.83" image! But if you changed the dpi header of the same file to 300, with no changes to the pixels, it would come in at 4"x5".

99% of the confusion over "dpi" can be traced back to the graphic arts industry. Ironically, trends in the development of later page layout software cured the problem for the photo industry. The "bounding box" approach used in QuarkXPress influenced most lab software. Kodak used "nodes", which were defined objects on a page of output. They were part bounding boxes, part database fields, and had all sorts of properties. That rendered the dpi headers in EXIF files mostly useless. But because lab systems had to connect to the graphic arts world for some purposes, we always populated the headers with 250 dpi at size...

The Capt.

Monitors do not have dots the resolution of some monitors can be changed, as in the display could be 1920x1080 or some other number. It is not a number of dots or pixels on the monitor.

frangeo Loc: Texas

Software!!!! Scanners pick up a LOT of dust.

burkphoto Loc: High Point, NC

Only if you don't understand how to deal with dust.

I had my scanner in a location surrounded on three sides with black plastic landscaping material taped to the walls. Rubbing that with an old wool sweater before a scanning session effectively sucked all the dust in the air away from the scanner. Then cleaning the scanner bed with a very slightly damp microfiber cloth got rid of the dust on the glass. Yes, there were a few remaining dust particles, but Digital ICE (iSRD if you use SilverFast as the driver) got rid of many of them. That's a hardware/software feature that removes dust and scratches.

Now I CAMERA SCAN my film. This white paper explains how I do it.

Attached file:
(Download)

The Capt.

I called Epson and asked them what to use for enlarging pictures. The 12000XL was recommended.
It can scan at 4800 dots per inch. I still don't know about the quality but with a price of $4000 it better be good.
https://epson.com/search/?text=12000xl

burkphoto Loc: High Point, NC

It will definitely do a good job, if you need to enlarge up to 12x17 inch originals. The optical resolution is 2400dpi. The 4800dpi figure is just the stepper motor movement. It scans in half-line increments. That improves image smoothness a bit, but resolution is 2400.

Just know that scanners like that are slow. If you were to use a high megapixel count camera and macro lens on a copy stand or tripod, and light your artwork with color correct lights from the correct angles, you could achieve similar or better quality in less time.

At the photo lab I worked for, years ago, we had three UMAX scanners that were very similar to the Epson 12000XL, right down to the specs. They were very good for scanning batches of small prints for school memory books (elementary school yearbooks). We also had a huge copy camera for making large composites (before the digital era). It could copy paste-ups of prints up to 60" by 40" onto Vericolor Internegative sheet film up to 14" by 11". These days, I would use a high megapixel full frame or medium format camera to copy art that big.

The Capt.

Thanks for the info.