How can I save my RAW file at the highest quality possible?

I'm shooting on a Canon EOS 20D taking 8.2MP RAW photos. I'm using Photoshop CS3 RAW software to edit the pictures, and I want to save them as high of quality as I can so that they can be blown up and put on a wall. I need them to be as big as possible. I know I want to save them as a TIFF file, definitely not a JPEG, but the question is, how exactly can I make sure they're the highest quality?

When I'm in the RAW software, I click the "Save Image" button and I can save it as a TIFF, but I don't have a lot of options for settings. Here's an example of a file I saved as a JPEG and as a TIFF. They have the exact same dimensions, but the file size of the TIFF is larger:

3504 x 2336 pixels, 14.6 x 9.733 inches, 240 pixels/inch
JPEG File Size: 3.1 MB
TIFF File Size: 23.4 MB

What I want to know is, is this as high as it will go, or is there something I can do to make it even higher quality? Can I save it with larger dimensions, or do I even need to? Is the TIFF file simply enough information to make, say, a 30 x 45 print? What about a 50 x 75?

Thanks in advance for any help you can give me.

Your TIFF file is created with a less efficient compression algorithm, but also one that doesn't loose any of the data (most probably in this case). That's why it's so much bigger as a file, but not as an image.

Since the jpeg algorithm is pretty good at keeping what's important, but throw away things you'll not see anyway, chances are pretty good that even if you make large prints, you can't tell which file was actually printed. The advantage of the large file format lies more in the ability to post process it, change colors and such.

its all about DPI (dots per inch) open your file in cs3, go under image, then image size, and then unclick resample image, this will put a bracket on the sides and resolution, now click on resolution and change it, this will change the size, 350dpi is the best your printer can do (there might be higher ones but not that i have ever used) and you can lower it to say 200, this will make the image bigger but your loosing dpi (quality), you can go as low as around 150 with the image still looking "ok". on my prints i never go under 200, just my prefrance. Your 20D with its 8mp wont get you a wall size print with great detail...but you can play around with it and see the sizes you can go. you can change the size without changing the DPI but cs3 will fill the pixels with what it thinks will work, not always the best idea...

Hmmm, this helps, but I'm still a bit unclear. Andy, when I change the dpi of the file manually does it actually improve the image quality, or just add more dots of the same color in between? Will it actually look better when it prints?

I've been trying to research this for the last few days and been really struggling, all of this printing stuff is so confusing. I was told by one very well-established printer that dpi actually has nothing to do with how good a picture will look, but it's the MB. So a 23 MB file will print way better than a 4 MB one even if they have the same dimensions.

Can anyone tell me specifically the largest prints I will be able to make from these three different example files? It would REALLY help me out!

#1) a 9.3 MB JPEG file:
3504 x 2336 pixels
48.667 x 32.444 inches
72 pixels/inch

#2) a 3.2 MB JPEG file:
3504 x 2336 pixels
14.6 x 9.733 inches
240 pixels/inch

#3) a 23.4 MB TIFF file:
3504 x 2336 pixels
14.6 x 9.733 inches
240 pixels/inch

yes it fills in which if done to bigger sizes can make it look really bad. your kind of stuck with the 8mp camera, if you want HUGE prints you will need something with more mp (5dii?) or stick a bunch of photos together to make a large image with good resolution. if you take more zoomed in photos say 4 of the same subject you can stitch them together so it would look like a photo taken with a wider lens but with 4x the resolution

tienbien wrote in post #11642117
I've been trying to research this for the last few days and been really struggling, all of this printing stuff is so confusing. I was told by one very well-established printer that dpi actually has nothing to do with how good a picture will look, but it's the MB. So a 23 MB file will print way better than a 4 MB one even if they have the same dimensions.

He's mostly right. DPI is meaningless in general. But it's the number of pixels in the image that matter, not the size in MB.

You can get a top quality print at 300 ppi, and one very nearly as good at 180 ppi.

In all these cases you can get 292 ppi in an 8 X 12 print and a 175 ppi print in a 13 X 20 (approximately) print.

All the photo printers I've seen require a JPEG image, so the TIFF would have to be converted to JPEG anyway.

-js

All three are exactly the same size, 3504 x 2336.

If that was the original dimension of the image (out of the camera).

ppi/dpi does count as does resampling to a larger size...lets say 7000 x 4600 (more or less),

If the original image was 3500 x 2300 pixels and you resampled it be 7000 x 4600 it would not be as good compared to an original (out of camera) image that was 7000 x 4600

The only thing that counts is the original unresampled pixels, when thinking how large can I go. An original 3500 x 2300 is a little bigger than 10 x 6.5 at 300 dpi

3500/300 = 10.1n

So, the printer, saying a "larger file" means larger original, un resampled file, which is pretty meaningless unless you own cameras with different density sensors.

So, how big can you print a 3504 x 2336 image. Typically, labs want 300 dpi, depending on their printers. My lab prefers 400 dpi for prints up to about 20" and 300 for larger, 150 for banner/poster sized.

These numbers are the optimal size... in other words, larger files (more pixels) than 3500 for a 10" inch isn;t going to get you a higher quality image. Anything larger than 10", the image will start to look less sharp. How far can you go before it is unacceptable to you.. well, only you can answer that. You could easily get away with printing twice as large, let's say a 20" inch image from that 3504 sized "original". It all depends on where/how the image will be viewed. Billboards for example, are very low DPI since they are intended to be viewed from a far distance.

PS: That reads about as clear as mud

EDIT: you guys beat me to it

DPI means NOTHING in digital images. Your image only has dots, no inches, in a computer. You don't get inches until you print it on a certain size paper, and then you can work out the dots per inch. Your image has 3504 pixels(dots) on the long end. This means that if you printed it on paper 35" long, you'd have about 100dpi. What is specified in the file has no actual meaning as you can easily print on any paper. If you printed the same exact file on 1" wide paper, you'd have 3504 dpi.

What matters for print quality is the amount of detail and sharpness in an image. A sharp low res photo can print better than a mediocre high-res file. Generally for highest quality output you would want to stay above 150DPI and getting as close to 300DPI as possible.

As for the original question, there are no parameters for quality with a TIFF file because it always saves at the same (high) quality. JPEG has variable compression so can balance file size and quality. If you have the drive space, TIFF is the best option.

It is only the pixel dimensions which are important here.
The difference in the JPEG file sizes will be due to the amount of compression used - more compression means smaller file sizes but with less quality.
The TIFF is uncompressed and will be retain the most original information and is the one you should use for printing.
It has been widely accepted that for best quality prints the rule of thumb is to aim for 300pixels per inch (NOT the same as printer dots per inch......); so as your TIFF is the same size as the JPEGS they will all print to 3500/300 = 11.7" x 2336/300 = 7.45" ie around A4 in ISO paper size. BUT the most information will be printed from the uncompressed TIFF.
Note that the 300 figure is an ideal and prints made much larger, say down to 200pixels/inch may not look worse - remember that you view larger prints from further away normally..........
I have printed A3 from the same pixel dimensions as you quote and they are much better than good enough for display.

Thank you everyone for the responses, I am much clearer now. I appreciate all of your help.

Just a question for you guys in the know. Does it make a difference the Pixel Dimensions as apposed to resolution dpi and document size? Does one affect the other or has nothing to do with IQ on a large size print? Take for instance the following pictures. Both of these pictures are saved in jpeg form.

Print #1
Pixel Dimensions 1.00G
Width: 23200
Height: 15475

Document Size:
Width: 77.333
Height: 51.583

Resolution: 300

Print #2
Pixel Dimensions: 668.4M
Width: 18720
Height: 12480

Document Size:
Width: 78
Height: 52

Resolution: 240

Take Care,
Cheers, Patrick

number six wrote in post #11642185
All the photo printers I've seen require a JPEG image, so the TIFF would have to be converted to JPEG anyway.

-js

Just to clear up a little of the mud here
jpeg and TIFF are storage formats for RGB files. Once they are opened and displayed they are both RGB files. Your printer will be sent the RGB file which is converted into information for the inks in the printer.

Saint728 wrote in post #11642455
Just a question for you guys in the know. Does it make a difference the Pixel Dimensions as apposed to resolution dpi and document size? Does one affect the other or has nothing to do with IQ on a large size print? Take for instance the following pictures. Both of these pictures are saved in jpeg form.

Print #1
Pixel Dimensions 1.00G
Width: 23200
Height: 15475

Document Size:
Width: 77.333
Height: 51.583

Resolution: 300

Print #2
Pixel Dimensions: 668.4M
Width: 18720
Height: 12480

Document Size:
Width: 78
Height: 52

Resolution: 240

Take Care,
Cheers, Patrick

Pixels divided by resolution = print dimension. 18720 pixels /240 pixels per inch = 78 inches

Print resolution will determine how closely someone can look at the image before they discover its limits of detail. While many people will stand back from a big print to appreciate its entirety, some pictures invite closer inspection (landscapes in particular) so you need to be a bit more specific

If you want maximum information saved to disk, save your images as 32 Bit TIFF.

AJSJones wrote in post #11642745
Pixels divided by resolution = print dimension. 18720 pixels /240 pixels per inch = 78 inches

Print resolution will determine how closely someone can look at the image before they discover its limits of detail. While many people will stand back from a big print to appreciate its entirety, some pictures invite closer inspection (landscapes in particular) so you need to be a bit more specific

The two I was talking about were indeed landscape/sunset pictures. Thank you for the explanation you gave.

Take Care,
Cheers, Patrick