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I know this seems silly, but I really don't understand all this, I know 300ppi is the preferred pixel per inch ratio for photos, but how do you know how much you can do, like, I have a Canon 40D and 5D Mark II, how do I know how big I can blow up a photo and still keep 300ppi ... I mean if I put it through photoshop or lightroom, it allows me to make them 600ppi at 20x30 print, but I assume that some of those pixels are filler the program makes up in order to reach 600ppi ... how do I know the true limit of ppi I can get too in each photo from each camera, also if I crop something, how can I figure out how big I can make it before I loose that true 300ppi print?
Thanks!
Thanks!
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Re: 300 ppi/dpi questions
Thu, October 15, 2009 - 2:47 PMWell, 300ppi is not necessarily the truth. I've met printers where 240ppi gave better results than 300ppi.
I don't think there's a solid rule of thumb. I have a 70ppi print hanging on the wall outside my loft, and it looks quite good. However, it's also nine feet wide, so you don't tend to look at it up close.
Some images blow up better than others. Some interpolation routines are better than others.
In short, I'd recommend trying it. You may not want to make a full-sized print, but blow up the image to the size you want to print and then print a section from the photo at that resolution. Look at it at the distance you expect to be viewing the print from, and see how it looks.
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Re: 300 ppi/dpi questions
Thu, October 15, 2009 - 10:41 PMPatti's got a really good note and recommendation - larger prints don't get looked at so closely, and if you try just a section, you're not spending an arm and a leg to see how it looks.
If you blow up in PS, just go 10% or so at a time. Other than that, you might not have to blow up too much anyway. I'm shooting a lot with 6.1 MP Nikon D70s. I've enlarged to 20x30 and it looks really good. 12x18 enlargement I see no difference with comparing it to 8x12. I'm not sure, but I believe that the MKII is a lot higher resolution than mine.
There are lots of printers out there, but you might try Costco if you have one near and are a member. You can go to their website and download printer profiles, and when you upload, you check the box for FULL RESOLUTION, then near the end you choose options and set it to NOT auto correct. Costco prints 8x10 or 8x12 for $1.49, 11x14 or 12x18 for $3, and 20x30 for $10 (usually 20x30 is mail order).
Let us know how things turn out.
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Re: 300 ppi/dpi questions
Thu, October 15, 2009 - 11:52 PMPatti,
1. What's Interpolation, I've seen it thrown around, but it doesn't compute for me, lol...
2. I don't know how to pick a section and blow it up to the equivalent of what size I want it to print at.
UCP,
1. Yes my 5D Mark II's resolution is a lot higher than your Nikon's, and I believe the 40D is also slightly higher.
2. Wow, Costco sounds a lot cheaper than the place I go to, they are a professional photography store and they process their own film and prints in house, they are very good and I've observed that their prints are often of better quality than say Walgreens or CVS photo centers, probably Costco as well, but their prices are much higher at the pro shop, so maybe I'll switch to Costco for stuff that doesn't matter so thanks for that.
Anyone Else,
This seems like a lot of "work around" to 'figure out' what I can blow up as a rule per camera, but what about cropping, there's got to be a feature in Photoshop, or preferably Lightroom (because I hardly ever use Photoshop because it's too complicated for me and Lightroom is specifically designed for photographers so the work flow is fast) that will calculate the "natural" optimal size per photo. -
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Re: 300 ppi/dpi questions
Fri, October 16, 2009 - 1:50 AMStone,
I was up, and I'm betting Patti will reply, but figured if you were up as well you might want some quick answers.
Interpolation: In general terms, it's filling in unknown values in a sequence by examining known values (my best subject was math). For Ps/Lr, etc, that would mean that when you enlarge it the pixels are going to stay similar in size and the software will fill it in with other pixels by examining others.
If you're creating a 20x30, say, first, create a duplicate of the image. Then select an area (I'd pick the spot that seems to be least in focus) and crop to just that area, maybe to a 5x7 or 8x10 crop. Then print that. A lot cheaper to print a 50 cent 5x7 than a $10 (or more) 20x30. If the area that seems to be least in focus appears well, it's likely the rest of the image would print well also when you print the uncropped one.
Costco is likely comparable to a lot of the professional photography stores. I've seen the stuff from Walgreens, Longs, CVS, Target, and even Kinkos. None of it impressed me. I've also seen the stuff from a lot of the professional shops, both locally (I'm in the San Francisco Bay area) and mail order. Costco compares to the best of them.
If you can find one (or rent one), get a Spider (not completely sure of the name) and it'll calibrate the color of your monitor comparing it to a print. There is also software to do this as well.
If you print at Costco, use the do NOT autocorrect option and download their printer profile. If there is more than one printer at the store you can call them to get the specific one. If you're a member, you can log in and you'll see a link for PRINTER PROFILES, and it will direct you to www.drycreekphoto.com/icc/ That page will let you pick up by state and then city. Funny - I see a lab I used to use (Village Photo in Old Saybrook - I lived there for 30 years). Same printers as Costco. That page also has a link for "How to use profiles for printing" and will walk thru a lot of info.
I know a lot of this is off the original subject, but thought it might be some good info.
Best wishes
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Re: 300 ppi/dpi questions
Fri, October 16, 2009 - 5:25 AMUCP it was great info, thanks!
I think I'm asking for two things, one is 300ppi without Interpolation, since I want the true pixels size, no filler. And two, I haven't checked the costco site, I'll do that later, but I hope they can do all that with Mac software, I find a lot of places forget about people that use Macs, which is dumb since thats what MANY photographers use.
Thanks again.
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Re: 300 ppi/dpi questions
Fri, October 16, 2009 - 10:41 AMA while ago, I did a test wherein I took a small section of a photograph and tried out Photoshop's various techniques for resampling. The demos are here: www.flickr.com/photos/whi...7368242691/
Note that you need to be logged into Flickr to see them full-size, which is the only size that's interesting. -
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Re: 300 ppi/dpi questions
Fri, October 16, 2009 - 11:46 AMThis is interesting, though I don't really know how to do any of that, I don't even know what the different names mean, let alone how I would go about saving the files in each kind or whatever you do, man I sound like an idiot, I'm really very intelligent, I just don't know about image info, I learned to shoot before digital existed and before photoshop was created, and I'm having trouble connecting to digital as a medium. I don't understand why it can't be intuitive and easy like, isn't this a normal issue, wouldnt you think they would put a built in information code that could just tell you (this is the largest possible size at this given ppi before degradation of the image) or something like that? It should just be a standard feature. Am I wrong? -
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Re: 300 ppi/dpi questions
Sat, October 17, 2009 - 12:15 AMSo let's say that you have a 1x2 pixel image-- the simplest image that will make this an interesting question. It looks like this:
WB
Where the W pixel is white and the B pixels are black. It's a pretty boring image, but let's roll with it.
Let's say that you want to blow it up so that it's one pixel by three pixels, so you resize it in Photoshop. Photoshop will have to "make up' a pixel in between the two that exist. You'll wind up with this:
WXB
Where W is white, B is black, and X is... what? It's an interesting problem. Photoshop has to make up data to go in between the two existing pixels.
Photoshop has several different algorithms for deciding at what should go in the middle. If you use an algorithm that makes the image sharper, you might wind up with C being either white or black. If you use an algorithm that makes the image smoother, you'd wind up with something like 50% gray in between the black and white.
In fact, I just tried the various resampling algorithms in Photoshop on exactly that image. Here's what I got:
Nearest Neighbor (preserve hard edges): BWW
Bilinear: BGW
Bicubic (best for smooth gradients): BGW
Bicubic Smoother (best for enlargement): BGW
Bicubic Sharper (best for reduction: BGW
What I did was to create a test image in Photoshop, then go Image, Image Size, typed in the new pixel dimensions that I wanted, then under Resample Image I picked one of the five resampling methods.
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Re: 300 ppi/dpi questions
Sat, October 17, 2009 - 12:22 AMAnd no, it shouldn't be a standard feature, because there is no one answer for how large an image can be enlarged before it degrades. A lot depends upon your print technology, the image itself, and what a typical viewing distance would be for an image.
In practice, I don't think there *is* a maximum enlargement size. I'm pretty sure I could take an 8 megapixel image out of my old Rebel XT and turn it into a billboard and it would look just fine. The trick is that you never look at a billboard from close-up-- you're always 50+ feet away from it. I'm currently working on printing one of my old 8MP images at 28x42". Preliminary test prints indicate that it will turn out just fine. Again, the trick is that a normal viewing distance for a 42" photo is like 5-10 feet-- you don't normally look at it from a foot away. -
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Re: 300 ppi/dpi questions
Sat, October 17, 2009 - 2:46 PMI know this must be hard for you to understand, but I don't want filler, I want the original image with no made up pixels, so I just wanna know how large a 10 and a 20 megapixel image will be able to be blown up at 300ppi. Maybe I'm missing the point I think I am. Say I want a 2 foot by 3 foot, or 4 foot by 6 foot image for a gallery show, people will naturally be looking at it closer than if it were a billboard, so I'm wondering if I'll have to go with medium format or I can stick with my 5D mark II and the image still look crisp. -
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Re: 300 ppi/dpi questions
Sun, October 18, 2009 - 1:05 AMOK, so this is fairly simple math. If you have a 3000x2000 pixel image, at 300 PPI it will it will be 10x6.6 inches. If you print it at 200PPI, it will be 15x10 inches. All you have to do is divide the number of pixels by the PPI that you're printing it at to get the maximum size.
However, yes, you're sort of missing the point. Interpolation is the tool that it used for blowing up images. I've printed an 8 megapixel image 42" wide, and it looks just fine. I would not hesitate to print my 5d Mark II images at 4x6 feet. The prints will look just fine. Interpolation will often happen "behind the scenes" whether you intentionally do it or not.
By the way, the typical viewing distance for a 4x6 print is on the order of 10 feet, I believe.
Here. I found this while googling around. It may give you the information you want:
www.photokaboom.com/photogra...tance.htm
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Re: 300 ppi/dpi questions
Sun, October 18, 2009 - 7:32 PMsweet thanks!!!
you're so awesome guys!! and Michael if you have any thoughts, please chime in :) -
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Re: 300 ppi/dpi questions
Sun, October 18, 2009 - 11:46 PMOh, one other thing. Interpolation isn't a bad thing, and it will often happen "behind the scenes" when you make a digital print even if you don't intentionally do it. I believe that printers and printer drivers do it all the time.
Like many things in digital photography, automatic processing will often do a pretty good job, but eventually you might want to learn to manage it yourself in order to get better results. You may not ever need to, but it's good to know that it's going on just in case it ever bites you in the butt. -
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Re: 300 ppi/dpi questions
Mon, October 19, 2009 - 6:12 AMYou're right about that, I really need to educate myself further, it's a question of time, money, and fining a class that will teach me what I don't know, and not be all about what I do know. After all most photography courses will teach photography, something I don't really want to re-learn, I'm one of those people who likes to find their own way of doing things, so I can be difficult as a student (and I know it) and I find I'm able to find other ways to do things that I like.
Anyway, again thanks! :) -
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Re: 300 ppi/dpi questions
Mon, October 19, 2009 - 8:29 PMStone, Patti, and other esteemed photographers,
I do wish I could have contributed more to this thread, but I was totally tied up for last few days at photo shoots.
My sense reading the dial that has ensued is that Patti answered in detail all of your queries in a manner quite similar to what I would have, so I'm going to affirm kudos to her!
Blessings and Light,
M
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