Newbie enlarged print questions

[markush]

I'm sure this is a simple question and if anyone can point me to a good tutorial I would be grateful.

Just went digital with the Canon 20D and I need to make a 16x20 print. A photo taken in RAW converted to .TIF with the Digital Photo Professional software when opened with Elements 2 gives me a document size of 10.011 X 6.674. There is an option to resize when I convert from RAW with Photo Professional, I can also change the DPI when converting and the default is set at 350 DPI....should I use that or should I do any upsizing with Elements? If i should just use Elements can someone walk me through how I would resize to get the best quality 16X20 print?

[Hellashot]

You dont need to deal with DPI. All that you'll be concerned with is your print size. You have no control over the DPI when you're enlarging an image like you want to. The DPI will end up whatever it is after you crop it in a 16x20 proportion, then enlarge it.

[CyberPet]

If you want to interpolerize (spelling?) an image to be larger than the actual size. The best is to use small steps in Photoshop. Use Bicubical softer and increase the size 110% each time until you reach the right dimensions. Quickest way is to make an action macro and just hit the button until you reach the desired size. Set the pixles/inch to something between 212 to 300 for best results.

[InskiP]

I was wondering about this too. When you shoot in RAW mode how big can you enlarge your image? RAW images don't have a DPI/PPI? Confused, sorry, also a newbie...

[Curtis N]

Open suggestion for our wonderful, hard-working moderators:
I think it would be great to have a "sticky" thread dedicated to "DPI" and all of the misconceptions surrounding it. Perhaps an appropriate title would be, "FORGET ABOUT DPI."

Here's a link for starters.
http://www.photo.net/learn/resize/

[robertwgross]

Part of the confusion on this topic comes from our terminology.

When you shoot a RAW image, it has no real dimensions. It is so many pixels by so many pixels, perhaps yielding 8 megapixels total. By the time you get it converted into a TIF file, there has been a DPI tag placed on it, and megapixels divided by DPI squared will yield dimensions in inches. If you are trying to go from there directly to a large print, you can do it, but the large print may have a reduced DPI on it. Maybe something low like 100 or 150 DPI.

Some users will argue that you will get better results by increasing the total number of megapixels. We can't change the actual sensor, so the only way to get there is by a resampling of the existing 8 megapixels. By a careful process, you might increase that to 16 or 24 megapixels total, and then you can do the large print from there. That print may have a higher DPI number that what you had previously.

However, other users will argue that you haven't really gained anything. They will argue that the first method and the second method result in the same print quality. The bad part about the second method is that it takes more storage for the larger file, and it takes longer to fool with it.

I suggest that each user should try this and see which method works best, because there is no clear winner.

One of the dirty little secrets involves going from TIF, which might have an 8-bit or 16-bit color depth per channel, to JPEG, which is only 8-bits. Sometimes JPEG has lost some of the color depth, and sometimes that is noticeable. Sometimes not.

---Bob Gross---

[markush]

Hopefully I wrote this in a way that will make sense to someone other then just me. By my following questions you can tell I really need someone to hold my hand through this.



From reading what everyone has posted in this thread, here are the steps I beleive i should follow (this is also called workflow correct?)



1. Using Digital Photo Professional convert from RAW to TIF....I notice the DPI I choose in this step is the resolution in PPI in the PhotoShop resize window. I know they are two different things so why is the DPI I chose in DPP the same number that pops up as PPI in PhotoShop? Also...and this is the part where I totally get confused on what to do....the DPI I choose when converting to TIF in DPP changes the document size in PhotoShop. If converted with a 300 DPI I get a starting document size of 7.787in X 11.68in and with 350 DPI a size of 6.675in x 10.011in. What should I do here?



2. Crop the image to the final proportions (16x20). When I crop should I specify a 300 PPI resolution? If I don't input a number when cropping my PPI resolution goes to about 145.



3. Do any sharpening or retouching necessary.



4. Get this thing to the printer and be done with it!!

[robertwgross]

Markush, re-read my post.

If you are trying to achieve a 16x20 print with 300 DPI print resolution, you are going to have to use about 29 megapixels. You haven't got that coming straight out of the 20D camera sensor, do you? No, you've got about 8 megapixels. So, you have only a few alternatives:
(1) reduce your 300 DPI requirement downward to something much more realistic
(2) do interpolation to increase your file by a factor of 3 or 4
(3) change your intended print size downward

---Bob Gross---

[Curtis N]

markush,
When you take (or upload) your digital file to a print lab, they won't care about the DPI setting. They will enlarge your image to fit the print size you order.

I have had prints of many different sizes made from digital files varying from less than 2 megapixels to over 6 megapixels. I never even look at the DPI settings on the files. It's an irrelevant number.

[markush]

I apologize Bob, I had read your post quite a few times before I posted my intended steps....I made a mistake and left out the interpolation part which should have been step #2. What I wanted to get across with that last post was that I wanted to start with the best possible image after converting from RAW. Being able to change the DPI when converting to TIF and thus affecting the dimensional size of the image when opened with PhotoShop threw me for a loop.

[robertwgross]

Yes, that's right. Starting from a fixed image size of megapixels, if you increase the DPI number, then you decrease the inches of dimension, and vice-versa.

How you choose to get to the big print depends on whether you are doing it yourself or sending the file off to some print shop.

Personally, I will print the big print directly from the file and see how that works. In some cases, I will do a bunch of interpolation steps to increase the file size, and then print that directly. I have never convinced myself one way or the other for which is the better method. It seems to vary with the details of the image file.

If I were sending the file off to some print shop, then it seems counter-productive to do the interpolation, then send off the larger file. They could have done that themselves. Transfering a smaller file seems smarter. However, every different print shop has different capabilities and standards and methods. Try it different ways and see what works best for you.

Once I got a little carried away with that interpolation stuff. I had one excellent file that I was fooling around with, and then I noticed that my whole computer was getting bogged down. Then I noticed that the new file size was 600 megabytes or something. Geez!

---Bob Gross---

[InskiP]

I don't know if I will ever get this part of digital photograpghy through my thick skull???
So basically I just send the lab my file and ask them to enlarge it and they'll take it from there.
I don't have to mess w/ image size or resolution(DPI/PPI). Is that what you're saying?
Does it make a difference if my image is edited and not straight out of the camera? Doesn't a RAW file have a resolution?

Another thing I noticed is that my images are an odd size, like I can't get an actual 8x10, it ends up being 10x6.67 or 11.68x7.792. Is this because of the size of the sensor?

Sorry to be so think, but I'm still a newbie transitioning from film...thanks

[robertwgross]

So basically I just send the lab my file and ask them to enlarge it and they'll take it from there.
I don't have to mess w/ image size or resolution(DPI/PPI). Is that what you're saying?


As I stated previously, it depends on where you are sending it. Most shops will operate on the basis of you sending them the file and specifying a final print size. Then they do the work. However, if you send them something that does not make sense, you will have to reconcile that. For example, if you send a file that has a 3:2 aspect ratio, and if you request an 8x10 inch print, SOMETHING is going to happen, and it may not be right.


Does it make a difference if my image is edited and not straight out of the camera? Doesn't a RAW file have a resolution?


The camera places a DPI number on the file, but that means just about nothing. You are shooting RAW, aren't you? Virtually no file is going to come straight out of the camera.


Another thing I noticed is that my images are an odd size, like I can't get an actual 8x10, it ends up being 10x6.67 or 11.68x7.792. Is this because of the size of the sensor?


Aspect ratio screws up many a user of commercial print shops. That is why I now do all of my printing myself.

---Bob Gross---

[InskiP]

Aspect ratio is definately screwing me up...How in the world do I get an 8x10 print from either a lab or my own printer? I guess there will be cropping involved??? Unfortunately, I like my in camera crops. Why did they do this to us? Why oh why didn't they just make the sensor like 35mm size? There's no end to what I have to learn...

[Curtis N]

Why oh why didn't they just make the sensor like 35mm size?The aspect ratio of the 20D and most other digital SLRs is 3:2, just like 35mm film (36mm x 24 mm negative).

Most point & shoot digicams, on the other hand, have a 4:3 ratio (it matches the aspect ratio of most computer monitors).

The print labs I have dealt with, if they receive an image that does not have the correct ratio for the print size ordered (which is probably 98% of the time for consumer labs since most of the files they get are straight out of a P&S camera and the customer orders 4x6 prints), will crop equal amounts off the top & bottom or equal amounts from both ends to make the image fit the print.

Since this is generally NOT what you want, it's important to crop to the correct ratio for the print size you are ordering. All of the good image editing programs (Photoshop, Paint Shop Pro, etc.) have several standard ratios for cropping that make this fairly effortless.

If you're ordering a 20 x 16 print (5:4 ratio) and you really need to save both ends of your image, make your canvas larger to create some white space on the top & bottom. Then when you get the print you can crop or matte appropriately.

As Bob Gross mentioned, doing your own printing can be less problematic in terms of aspect ratios, but not many of us have printers that can handle 16 x 20.

[robertwgross]

The sensors in all Canon EOS digital cameras have the same aspect ratio, 3:2, which is the same as 35mm film.

So, to get an 8x10 print, the same cropping task exists.

---Bob Gross---

[tim]

If you use a decent service to do your prints you're better off doing nothing. Go to this page (http://www.elcocolor.com/hot_internet_only_specials.htm) then click on their FAQ.

[R1 Kid]

If you want to interpolerize (spelling?) an image to be larger than the actual size. The best is to use small steps in Photoshop. Use Bicubical softer and increase the size 110% each time until you reach the right dimensions. Quickest way is to make an action macro and just hit the button until you reach the desired size. Set the pixles/inch to something between 212 to 300 for best results.

Ditto- I use this method everytime and I love the results. Go pick up the book by Scott Kelby: the photoshop CS book for digital photographers. It steps you through this process and many many more usefull examples. Priceless book for learning some basic digital photog. steps.

[InskiP]

I read the link above, thanks. What confuses me is where it talks about specific size. It says if you want a 16x20 image crop in PS and resize the canvas to 20x30, why this larger canvas size?

With film I'm used to starting w/ a small image and increasing it, this is just the opposite.
I start w/ a 16x24. To get my 8x10 I went to image>size and entered 8 because in this pic the height is more important than the width. I now have an 8x12 image. With the crop tool I cropped my 8x10 section. It says to leave resolution blank. Then I went under canvas size which said 8x10. Am I supposed to increase it or something? If I follow these steps will I get an 8x10 back from the lab?

Now when I left the resolution blank weird things happened. First, it took a LONG time to crop. Then I ended up w/ a gray screen and a bunch of little squares that eventually turned into my image. HUGE file.

As far as the Scott Kelby book, I don't have Adobe CS yet, but I'll check it out. I was also going to check out Camera RAW for Adobe CS2 by Bruce Fraser. Is it the same kind of info? I don't want to get too many books w/ the same info since I'm on a tight budget right now...

Thanks