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01/15/2006 11:01:05 AM · #1
I am interesting in eventually selling prints.

In my exif data, it states that my dpi is 72, either side. Minimum quality is listed as 150 dpi.

Does this mean my camera isn't strong enough for sellable prints? Or is the dpi calculated in some other manner? In other words, if I take photos 3MB in size, and the 72 is still present no matter what size I take my photos in, does that mean they aren't good enough quality still for selling?

If not, guess I will just have to wait for upgrading. I know when I print them at home, they come out great and have even won ribbons. But not sure they meet minimum standard for selling at DPC.

Rose
01/15/2006 11:09:39 AM · #2
What size are your photos when you convert them to 300 dpi?
Or 150?

Physical dimensions..

Message edited by author 2006-01-15 11:11:22.
01/15/2006 11:47:22 AM · #3
What matters is the total number of pixels you have -- pixels-per-inch just measures how spread-out they are. For example, if you images is 3000 pixels in the long dimension, you can print:

3-inch picture at 1000 dpi

10-inch picture at 300 dpi

20-inch picture at 150 dpi

30-inch picture at 100 dpi

Just change the ppi setting in the Image Size dialog without resampling to see the printable dimensions at various resolutions. Or, enter the printed dimension you want and you can check the resolution it will be at.

Message edited by author 2006-01-15 11:48:08.
01/15/2006 11:48:07 AM · #4
You can print almost any photo at almost any size by adjusting the size of the photo in Photoshop or some such, but you won't necessarily get good quality prints. Try this ... In Photoshop go to Image>Image Size. Uncheck Resample. Set your PPI to 150 and see how the Print Size changes. That will be about as big as you can print and get sort of decent quality. Set PPI to 300-325. What did the print size change to? That will be a very good quality print.

You can resample the image to make it bigger with software like Genuine Fractals and there are others but it's extra software and cost to do it. But you can get good results up to 6 to 8 times bigger than the original.

Message edited by author 2006-01-15 11:51:41.
01/15/2006 12:38:57 PM · #5
This is where it all becomes GREEK to me. I don't know anything about this dpi stuff. And I don't use Photoshop but PSP8

Let me give you some exif data off a picture I will now take, and then you can tell me what is what maybe?

A photo I just took at 3MB F (97), my largest size in the best quality I think, says this in exif:

Width 2048 pixels
Height 1536 pixels
Horizontal Resolution 72 dpi
Vertical Resolution 72 dpi
Bit depth 24
Frame count 1
Then my camera
Color representation sRGB
Shutter speed 1/2 sec.
Lens F/4.8
Focal length 6mm
ISO 100
Exposure Compensation: -1.2 step

Now, given this information, what can I expect from a print, and using PSP8 specifically, what should or could I do and still have it printable YET, meet the size standards here at DPC to put in my port.

Rose
01/15/2006 12:43:13 PM · #6
at 150dpi, uncropped, your image would be about 13.65"x10.25"
at 300dpi, uncropped, 6.83"x5.12"

So if you were to sell on DPCPrints, you could safely do anything smaller than a 8x12, unless you used something like Genuine Fractals to upsize.

Message edited by author 2006-01-15 12:43:33.
01/15/2006 12:45:43 PM · #7
Originally posted by larryslights:

at 150dpi, uncropped, your image would be about 13.65"x10.25"
at 300dpi, uncropped, 6.83"x5.12"

So if you were to sell on DPCPrints, you could safely do anything smaller than a 8x12, unless you used something like Genuine Fractals to upsize.


Ok, so that is good! However, I guess my next question is how to convert them TO a dpi, and then, how to upload them here and be of size requirements for this site. This is not something I have ever done, and don't even know where to look. I don't believe I have seen the option before in PSP8.

How about an example for dummies?

Rose
01/15/2006 01:03:43 PM · #8
In PaintShop Pro 7:

1. Point to Image, then click Resize.

2. In the Resize window, click the Actual / print size button.

3. In the Resolution box, adjust the number for the Pixels / inch.

The Width and Height values change accordingly to indicate the resulting size of the image.
01/15/2006 01:03:59 PM · #9
I am sure that PSP has an "Image Size" command/dialog. When it comes up, make sure that any "Resample" option is not selected, and set either the DPI setting or the dimension setting -- they should change automatically with the other.
01/15/2006 01:06:11 PM · #10
I will try that. Thanks GeneralE and bowhenn. So this will give me an actual print size?

And then, General E, I would send you what size file through portfolio? The largest one? Or what was resized to the 640 allowed here?

Rose
01/15/2006 01:17:59 PM · #11
There are two upload buttons in your Portfolio. Use the one labelled to upload a Print image, and link that to your full-sized print image.

The site will automatically generate a portfolio image for you, either at 640 pixels or just a thumbnail (to save space) -- your choice. The print image does not count against your available portfolio space, only the smaller image.
01/15/2006 01:27:44 PM · #12
Dealing with the fundamental issue, let's see if I can explain how arbitrary dpi is as a term:

Let's suppose we were shooting film, and let's suppose I shot a square image of 10,000 beachballs arranged in a 100x100 square. The negative size is, let's say, 10x10 inches. Now let's suppose I made a 100x100 inch print of the beachballs by projecting through an enlarger to a large paper on a wall (this is how we used to do murals); each beachball would appear on the paper as 1 inch in diameter. Each beachball on the negative is a tenth of an inch in diameter. So this print represents a 10x enlargement.

Now let's make a "contact print", laying the negative down on a piece of paper and projecting light through it; this would be a 10x10 print, what's called "actual size" or "100%", and each beachball is a tenth of an inch in size. With me so far?

Now let's further suppose that the beachballs were of two colors, so they are arranged in a PATTERN; let's say a diamond within the square, red beachballs and yellow beachballs.

NOW let's stand back and look at the big print from across the room; what we see is not 10,000 beachballs but a red diamond on a yellow square. As we walk closer to the large image, we will reach a point when we no longer see the shapes but instead begin to see individual beachballs.

So the large print is a magnified version of the small print. If we view it from sufficient distance it's the "same thing" but as we get closer, the overall image loses coherency and the individual components become enitities in their own right.

The beachballs are your pixels. Your image consists of roughly a rectangle of 2000 x 1500 beachballs arranged in a pattern. The larger you print the image, the more distinct the individual beachballs become, and the further away from the print you have to stand to see it as a coherent image.

If you've ever gotten up really close to a billboard made by photo-reproduction, you know exactly what I'm talking about; the image disintegrates. But at a normal viewing distance of, say, 100 feet, the individual "beachballs" of the billboard are not distinguishable.

DPI or PPI is simply a "description of enlargement"; the lower the number, the larger the image and the "coarser" it is. Acceptable DPI for printing is basically based on the assumption that the print will be viewed at arm's length. 150 is adequate, 300 is excellent, as far as "visual sharpness" goes. Larger prints meant to be seen at greater distances can have lower values, but if you go up close to them they disintegrate into visible "graininess".

As general and bowhen have pointed out, there will be an interactive dialogue box in PSP where you can change either the ppi value or the print dimensions, and the other value will autmatically change to show you what you have. You can also force a resampling by checking a box, to increase or decrease the ppi at a given, defined size, but that's a whole other topic.

Robt.
01/15/2006 01:31:13 PM · #13
I make the analogy using square mosaic tiles, but otherwise the same -- thanks for the elaboration : )
01/15/2006 01:44:50 PM · #14
Great explanation, Robert!

Now please explain how Genuine Fractals (could I have a link to that, pretty please?) can upsize without loss of quality.
01/15/2006 01:50:39 PM · #15
All upsizing ultimately involves spreading the original tiles (or balloons) out, and filling the resulting spaces with new pixels, whose color value is determine by applying a mathematical algorithm to the surrounding (existing) pixels.

Photoshop alone has at least four different sampling methods; I don't know the particulars of the methods used by GF or any of the other dedicated programs, but the general principle should remain.

Message edited by author 2006-01-15 13:51:06.
01/15/2006 02:00:15 PM · #16
Aha..... thanks, General.
Judging by the replies earlier in the thread, GF does a much better job of it than photoshop, but there seem to be different versions of GF... which one would be needed to produce biggish prints (say for DPC prints)?
01/15/2006 02:55:49 PM · #17
So many people get confused with this topic. I am looking at submitting to a local juried competition and at the bottom of the Application PDF it says, "*All images submitted digitally must be minimum 1200x1800 pixels per inch."

Now I know what they really mean, but do they? PPI and DPI are not important in this context, but it's surely going to confuse some entrants.
01/15/2006 05:03:14 PM · #18
Other things to consider on prints and DPI - viewing distance and detail.
Normal viewing distance is said to be twice hte diagaonal of the print, so a 4x6 is normally viewed at 15 inches. An 8x10 at 27 inches. You can print an 8x10 at 150dpi and have an acceptable print for 27 inch viewing distance - depending on the image. A portrait is fine, no great detail needs to be preseerved. A close up of a cat may lose some detail - yo umay not notice unless you compare it to a 300dpi 8x10 print of the same image.

I try to keep all my dpi above 200 (so an 8x10 needs a file of 1600x2000). Seems to give acceptable results and the math is easy! I have done a 10x13 at 169 dpi (a pretty severly cropped original) and it looked fine an much less than the normal viewing distance.

I have tried a few upsampled images as tests in smaller sizes and they look fine - to me, even next to the 'original' higher dpi print.

All this assumes you have a good image to start with. A noisy image will not print very well at a low dpi count.
01/15/2006 05:55:03 PM · #19
Originally posted by Beetle:

Aha..... thanks, General.
Judging by the replies earlier in the thread, GF does a much better job of it than photoshop, but there seem to be different versions of GF... which one would be needed to produce biggish prints (say for DPC prints)?


Go here to get a trial download of Genuine Fractals.
01/15/2006 06:08:11 PM · #20
Originally posted by Digital Quixote:

Originally posted by Beetle:

Aha..... thanks, General.
Judging by the replies earlier in the thread, GF does a much better job of it than photoshop, but there seem to be different versions of GF... which one would be needed to produce biggish prints (say for DPC prints)?


Go here to get a trial download of Genuine Fractals.


thanks for the link
01/15/2006 06:21:25 PM · #21
Regarding Genuine Fractals, //www.fredmiranda.com sells "SI Pro" And "Resize Pro", both of which many very savvy users out there say do a better job than GF, and they are a fraction of the cost. SI Pro is the one I use for upsampling, and it works very well indeed. I have Resize Pro also because it works for a larger variety of resizing tasks, but it won't upsample properly on sharpened work, so I still use SI Pro because it works better in my established workflow.

Resize Pro is an EXCELLENT tool for quickly and cleanly DOWNsampling to 640 pixels. I highly recommend it.

R.

Message edited by author 2006-01-15 22:53:17.
01/15/2006 06:29:34 PM · #22
Originally posted by Bear_Music:

Regarding Genuine Fractals, //www.fedmiranda.com sells "SI Pro" And "Resize Pro", both of which many very savvy users out there say do a better job than GF, and they are a fraction of the cost. SI Pro is the one I use for upsampling, and it works very well indeed. I have Resize Pro also because it works for a larger variety of resizing tasks, but it won't upsample properly on sharpened work, so I still use SI Pro because it works better in my established workflow.

Resize Pro is an EXCELLENT tool for quickly and cleanly DOWNsampling to 640 pixels. I highly recommend it.

R.


That should be //www.fredmiranda.com/ ;)
01/15/2006 08:43:22 PM · #23
Thank you everyone for your replies. I "think" I understand it, but I will try it out on some shots I got on today's excursion. I will just enter one for DPC Prints and if its not acceptable, I will be told why, I imagine. And then I will know what to do next.

I am not really interested...LOL..to be honest with you, on what is or isn't a ratio or a dpi. What I am really interested in is what to do to the photo in order to have it be acceptable. I really like things just simplified - take photo - do this or that to it or don't do this or that to it - send to us - we do the rest. LOL....

So I will test the system and learn as I go that way just to see what happens. I'm one who is not good at learning by reading directions, but being told how to play. So I appreciate all the replies. Now lets see if I can apply them. :)

Rose

Message edited by author 2006-01-15 20:44:34.
01/15/2006 09:30:55 PM · #24
Ok, I just tried a print. I didn't need to crop it or do anything to it. This is what it says after resizing using resolution of 149.000 which I didn't change, and it basically says the print size is an 8 x 10. Resampling is off. And I didn't touch or adjust the resolution. Here on the site, after uploading, it says this:

Your image is 1600 x 1200 pixels, which translates to an aspect ratio of 1.33:1. Based on these statistics, here's a list of the prints you'll be reviewed for:

(1.33:1 Aspect Prints)

18 x 24 Glossy Print (66 DPI)

18 x 24 Matte Print (66 DPI)

30 x 40 Matte Print (40 DPI)

30 x 40 Glossy Print (40 DPI)

KEY:
Based on image size, this print will likely be approved.
The image is in a low, but acceptable DPI range. Excessive resizing may result in rejection.
Image does not meet the minimum printable DPI of 150. See FAQ.

Your printable file is not large enough to meet the minimum DPI of any of the print sizes available for this aspect ratio.


I'm confused. And the last one I tried said that the ratio was off. It was something like a 1.37 and couldn't be used for a print?

So what am I doing wrong.

Rose

Message edited by author 2006-01-15 21:31:47.
01/15/2006 09:36:23 PM · #25
Thanks for the links and info from me, too. Now I know I was indeed looking at the real thing - although Robert's option is much more do-able (i.e. cheaper).
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