dpi suggestions

[Russ]

What are the recomended dpi settings for various print sizes. I know magazine print requires 300 dpi but what will work for 8x10, 11x14 and larger.

[Dick]

You also need the same dpi for larger prints.

A D30 produces a 4.8" X 7.2" photo at 300 dpi. If you want a larger print than you must "scale up" the photo via interpolation. Since the real pixels don't exist to do this the program must fill in the dots with estimates.

It is important to start with a high quality image to have any chance of producing a good blow up.

Photoshop interpolates via three techniques the most precise called "bicubic resampling"(default).

A Photoshop plugin called Genuine Fractals fills in the pixels using a propriatary system using fractal math. It is general viewed that the upper limit for high quality prints from a D30 using GF is 11X14.

I use Genuine Fractal and produce super 8X10 prints on my Epson 890 Photo printer. I print at 1440dpi. (The 890 is limited to 8 1/2 X 11 paper.)

[Russ]

So basicly I have to pull the photo into photoshop enlarge the photo to 11x14 or whatever and change the dpi to 300 dpi and I should get a decent print. Always print at 300 dpi.

[Dick]

Yes. Use "Image Size" or "crop". Keep the dpi at 300 and indicate the finished size you want. If you use crop you may increase the blow up ratio significantly more and begin to lose quality. The resultant print will let you know if you've pushed it to far.

[subq]

I have read that you need basically a dpi of 240 for photo printers. Some say that anything over this is overkill. Other say that is not the case. Most people seem to use a dpi of 300 while lots of people even use dpi of 360 especially on some of the Epson printers I have read that a dpi of 360 produces a better print.

[TLMelanson]

Dick wrote:
You also need the same dpi for larger prints.

A D30 produces a 4.8" X 7.2" photo at 300 dpi. If you want a larger print than you must "scale up" the photo via interpolation. Since the real pixels don't exist to do this the program must fill in the dots with estimates.

It is important to start with a high quality image to have any chance of producing a good blow up.

Photoshop interpolates via three techniques the most precise called "bicubic resampling"(default).

A Photoshop plugin called Genuine Fractals fills in the pixels using a propriatary system using fractal math. It is general viewed that the upper limit for high quality prints from a D30 using GF is 11X14.

I use Genuine Fractal and produce super 8X10 prints on my Epson 890 Photo printer. I print at 1440dpi. (The 890 is limited to 8 1/2 X 11 paper.)

[TLMelanson]

Dick wrote:
You also need the same dpi for larger prints.

A D30 produces a 4.8" X 7.2" photo at 300 dpi. If you want a larger print than you must "scale up" the photo via interpolation. Since the real pixels don't exist to do this the program must fill in the dots with estimates.

It is important to start with a high quality image to have any chance of producing a good blow up.

Photoshop interpolates via three techniques the most precise called "bicubic resampling"(default).

A Photoshop plugin called Genuine Fractals fills in the pixels using a propriatary system using fractal math. It is general viewed that the upper limit for high quality prints from a D30 using GF is 11X14.

I use Genuine Fractal and produce super 8X10 prints on my Epson 890 Photo printer. I print at 1440dpi. (The 890 is limited to 8 1/2 X 11 paper.)

There is no need to use any DPI over 240 on an Epson six cartridge printer. Why? 1440 divided by six=240. The printer is physically incapable of producing any greater resolution. Anything over 240dpi gives you nothing. (At 2880 the max would be 480dpi but would provide no greater apparent resolution on an 8X10)

The oversampling required for an 8X10 print is so small that GF offers no advantage over PS Bicubic interpolation--in fact some say at these small sizes, actually causes a degradation. GF was created for print houses making *very large* prints and posters/banners.
Fred Miranda's Stair Interpolation works better in my experience than GF and I have both programs. This will give you a slight advantage over PS interpolation. Though trying to see the difference at 8X10 would be as easy as counting how many angels were dancing on the head of a pin. :-)

[md34]

As the 10D produces a photo @ 180 DPI, and it is suggested to change this in Photoshop to 300 DPI,.. What exactly does this accomplish?

[md34]

A photo from my 10D is 3072x2048 @180 DPI which is 17.067 x 11.378. After changing the DPI to 300, the size becomes 10.24 x 6.827. I have read that it is best to print at 300 DPI, (I am using an Epson 2200) but if I want to print a lager photo, such as an 8x10 or 11x17, should I just leave the original DPI @ 180, or change to 300 and all allow the resample image box to remain checked? In other words, does it make sense to interpolate back up to the larger size after reducing the size by increasing the DPI?

Thanks for your help.

[Rob Larsen]

md34 wrote:
A photo from my 10D is 3072x2048 @180 DPI which is 17.067 x 11.378. After changing the DPI to 300, the size becomes 10.24 x 6.827. I have read that it is best to print at 300 DPI, (I am using an Epson 2200) but if I want to print a lager photo, such as an 8x10 or 11x17, should I just leave the original DPI @ 180, or change to 300 and all allow the resample image box to remain checked? In other words, does it make sense to interpolate back up to the larger size after reducing the size by increasing the DPI?

Thanks for your help.

As long as you don't have the "resample" box checked, you are not interpolating your image at all. The image print dimensions and dpi are functions of each other. When you change one without having the resample box checked, the other values will adjust to their corresponding relative values without altering your image data.

Therefore, when you do not have the resample box checked, you can use the tool as a calculator to determine "what if" scenarios for various native dpi and file sizes. This is similar to adjusting your shutter speed in Av mode and seeing different but equal aperture values.

I suggest once you determine your ideal print size, enter that in your image size dialog and then check the resample box and enter your dpi value. I try to interpolate as minimally as possible and have seen great output on my Epson 2000P at 240dpi.

[md34]

Thanks Rob, that's helpful. I have another question though - what is the difference in output quality between setting the print size by scaling % at the print preview stage, and doing as you are saying with the interpolation?

Thanks again.

[The Photo Tuell]

DPI is so over-rated. Try doing test prints instead of worrying about numbers. You can get surprisingly good results without using any interpolation.

All this talk of how 'it is generally viewed that the upper limit for high quality prints from a D30 using GF is 11X14' is BS. If a 4MP P&S camera (G2 or G3 is what I've used and gotten many prints from) can get high quality, award winning 12x18s with no interpolation then a 3MP DSLR should be able to get high quality 11x14s with no interpolation. I've even done 20x30 from my G2 with no interpolation and it looks great.

When cropping and getting ready to print I don't worry about DPI, I just get the right ratio for the print size.

[riku~]

I can't find a way to use my genuine fractal. I have installed it, and then what? What should I do? I want to enlarge my picture's dpi. Thanks.

[StewartR]

Russ, a lot of the information you've been give here is a little misguided.

The reason people recommend 300ppi is because that is roughly the limit of what human eyes are capable of distinguishing. There is little or no point ever printing at higher resolutions because you just won't be able to see the difference.

But of course you will appreciate that the further away from something you are, the less you can see the detail. So you don't need 300 ppi if you're making large prints or posters that will be on the wall. You only need 300 ppi if you're looking at something close-up .

On the Cambridge In Colour (http://www.cambridgeincolour.com/tutorials/digital-photo-enlargement.htm) web site, there's a resolution calculator. For somebody with 20/20 vision, it suggests:
350 ppi when viewing at 25cm
175 ppi when viewing at 50cm
87 ppi when viewing at 1m
18 ppi when viewing at 5m

Some of these resolution figures might sound shockingly low, but the science is sound. My 350D will give me 3456x2304 pixels. If I were to print at 100 ppi that would come out at (roughly) 36"x24", which sounds h-u-g-e; but as long as I don't stick my nose right uip against it, but look at it from say 1 meter / 3 feet away, it will loook good.

[gubak1]

What are the recomended dpi settings for various print sizes. I know magazine print requires 300 dpi but what will work for 8x10, 11x14 and larger.
300 dpi is in most cases excelent!