print sizes

[Cait]

While keeping resolution in mind, how big of a print size could you get with a Rebel XTi?

[Cait]

One more thing, I've heard that mpix and shutterfly both do great jobs with printing services, but just wondered if one is perhaps better than the other. mpix seems to have more options, and I like all the sizes you can pick from, but which one is more preferable as far as quality goes? Does anyone have any comments about the 'metallic' print paper, or the 'true digital B&W' options that they offer??

[Unkl Buck]

Depends a little on the resolution that it was captured AT. If it's a full res file, I would say 16x20 or 20x24 before you see "junk."

As for mpix or shutterfly, mpix hands down. Why? They are fun by Miller's. I would trust something from them before shutterfly anyday.

[Benji]

Your 10.1 mp camera will give you a file of approximately 30 meg. A nice 20 x 24 print can be made for a file in the 16 meg range.

Benji

[haraki74]

I second the Mpix choice, unless you have an account with Millers Lab.

[Cait]

Thanks for the help. I'm surprised that I can get decent pictures at 20x24, I thought that perhaps 16x20 was as big as I could go. I will definitely go with Mpix then. A few weeks ago I used shutterfly for printing some personalized note cards for a friend, and wasn't very thrilled with the way they turned out. Once again, what's the difference with Metallic printing and the tradtional color paper? Is Metallic worth it??

[Unkl Buck]

Metallic prints will have a shinier glow to them than a traditional color paper. I've found that metallic is good for some prints, but not all. Black backgrounds do not really show the "cool" factor. IOW, Colorful images will do better than black. It's similar to a laminate, but will also show creases and fingerprints more.

[jbimages]

Originally Posted by Cait

Thanks for the help. I'm surprised that I can get decent pictures at 20x24, I thought that perhaps 16x20 was as big as I could go. I will definitely go with Mpix then. A few weeks ago I used shutterfly for printing some personalized note cards for a friend, and wasn't very thrilled with the way they turned out. Once again, what's the difference with Metallic printing and the traditional color paper? Is Metallic worth it??

There is a bit of basic maths that will help you work it all out.

Your camera's large image size is 3888 x 2592 pixels - at this stage they are just numbers. Each pixel is a point in the image and tells the colour and luminance at that point.

To print an image you need to put these pixels on paper. If you decide to stretch this out so that you have pixels 10 per inch you could create an image 66' 8" long and 21' 7" wide, but you probably need to fly over it in a plane or balloon to see what it is.
If you stood on it you would see a collection of multi coloured dots.


If you pushed the dots closer together so there were around 70-90 per inch you will have something close to what you see on the computer screen. It varies depending on the screen size and resolution (800 dots across a 15" screen are closer together than 800 dots across a 17" screen) (My 24" monitor at 1920 pixels is 80ppi)


Jumping ahead. In order to have what look like continuous tone changes on paper and lines without jagged edges etc., the printer needs to put the dots a lot closer together. Once you find out how many dots the printer wants to place for every inch of photo you can work out how many dots you need in a photo.

Each pixel in the image file corresponds to 1 dot, so, if your printer wants to put 300 dots every inch you need enough pixels in you image to do this. If you don't have enough and tell the printer to print anyway, it will make up pixels where it doesn't have any - this results in jagged lines and fuzzy prints.

Enough of the background, we know you have 3888 x 2592 pixels to play with.

If you are going to print from a home inkjet or bubble jet you need around 270 pixels for every inch of photo. That gives you 14.4" x 9.6"

Some of online printing places use a different technology and can do a good print by placing 200 dots every inch, a printer resolution of 200DPI. They will give you a print 19.44" x 12.96

In practice you can increase the number of pixels in the image by resampling in a program like photoshop. More pixels mean a larger print size. I said before that you can just tell the printer to print at a particular size and let its driver create the extra pixels. Photoshop resampling does a better job and allows you to apply print sharpening after the resample.


I regularly print 30" x 20" on metallic paper from my 30D files. The printer I use wants files at 200DPI so I resample the image in photoshop to 6000 x 4000 pixels, sharpen and send.

[cdreid]

Ive printed stunning 11x14s and 13x19's with 8 and 10mp pictures using standard upsiziing algorithms in multiple photo programs. Using genuine fractals you can achieve mindblowing enlargement sizes with from what i can tell no detectable loss in quality (note the detectable). Remember once you get bigger than 11x14 noone. noone. is going to be viewing it "up close". That is large poster or sign size printing and only viewed from a distance that it isnt going to make a difference. If your selling someone a "family portrait" that is postersize and $$$$ it might matter.

[Lor]

Just sharing my test print here. I tried a 24x36 print from my 20D. I did everything in PS and send to whcc. From what my eyes can see, it looked pretty good. I have no hesitation selling portrait this size to the general family.

I also tried test prints with the metallic paper. It depends on the photo. IMO, some b&w and females are best suited. But it boils down to the person that is paying for it.

[EOS_JD]

Originally Posted by jbimages

There is a bit of basic maths that will help you work it all out.

Your camera's large image size is 3888 x 2592 pixels - at this stage they are just numbers. Each pixel is a point in the image and tells the colour and luminance at that point.

To print an image you need to put these pixels on paper. If you decide to stretch this out so that you have pixels 10 per inch you could create an image 66' 8" long and 21' 7" wide, but you probably need to fly over it in a plane or balloon to see what it is.
If you stood on it you would see a collection of multi coloured dots.


If you pushed the dots closer together so there were around 70-90 per inch you will have something close to what you see on the computer screen. It varies depending on the screen size and resolution (800 dots across a 15" screen are closer together than 800 dots across a 17" screen) (My 24" monitor at 1920 pixels is 80ppi)


Jumping ahead. In order to have what look like continuous tone changes on paper and lines without jagged edges etc., the printer needs to put the dots a lot closer together. Once you find out how many dots the printer wants to place for every inch of photo you can work out how many dots you need in a photo.

Each pixel in the image file corresponds to 1 dot, so, if your printer wants to put 300 dots every inch you need enough pixels in you image to do this. If you don't have enough and tell the printer to print anyway, it will make up pixels where it doesn't have any - this results in jagged lines and fuzzy prints.

Enough of the background, we know you have 3888 x 2592 pixels to play with.

If you are going to print from a home inkjet or bubble jet you need around 270 pixels for every inch of photo. That gives you 14.4" x 9.6"

Some of online printing places use a different technology and can do a good print by placing 200 dots every inch, a printer resolution of 200DPI. They will give you a print 19.44" x 12.96

In practice you can increase the number of pixels in the image by resampling in a program like photoshop. More pixels mean a larger print size. I said before that you can just tell the printer to print at a particular size and let its driver create the extra pixels. Photoshop resampling does a better job and allows you to apply print sharpening after the resample.


I regularly print 30" x 20" on metallic paper from my 30D files. The printer I use wants files at 200DPI so I resample the image in photoshop to 6000 x 4000 pixels, sharpen and send.

Your explanation started well but fell down when you compared pixels to dots which are totally different things.

My R2400 prints at a highest resoltion of 5760x1440DPI. I can assure you that each pixel DOES NOT represent one dot. Pixels and dots are not related at all. Pixels are larger than the dots my printer produces.

Also in printing, the resolution you need is very much down to the size of print you want. I print my A3+ images (from a 20D) at around 180ppi and the image looks amazing. Remember larger images are viewed from further away than your small 6x4s. This means that lower resolutions are generally ok. Even a 6x4 will look fine down to around 200ppi-240ppi depending on how fussy you are. You will probably not be able to tell the difference between 300ppi and 240ppi.

Also you seem to mix up dpi and ppi. Images are made of pixels and an image resolution should be set in ppi. Your printer will print at anything upwards of 300dpi depending on the printer. Your printer will therefore require a 200ppi image and will probably print it on a printer with a resolution of 300dpi or higher.

Now to answer the POs question. As you can print larger prints at lower resolutions, the maximum print size in reality is VERY big! Large billboards are printed at very low resolutions but because you view them from a distance, they look fine.

That said, I'd aadvise speaking to your print lab and ask them what they require.

[severoon]

Originally Posted by EOS_JD

Your explanation started well but fell down when you compared pixels to dots which are totally different things.

My R2400 prints at a highest resoltion of 5760x1440DPI. I can assure you that each pixel DOES NOT represent one dot. Pixels and dots are not related at all. Pixels are larger than the dots my printer produces.

Also in printing, the resolution you need is very much down to the size of print you want. I print my A3+ images (from a 20D) at around 180ppi and the image looks amazing. Remember larger images are viewed from further away than your small 6x4s. This means that lower resolutions are generally ok. Even a 6x4 will look fine down to around 200ppi-240ppi depending on how fussy you are. You will probably not be able to tell the difference between 300ppi and 240ppi.

Also you seem to mix up dpi and ppi. Images are made of pixels and an image resolution should be set in ppi. Your printer will print at anything upwards of 300dpi depending on the printer. Your printer will therefore require a 200ppi image and will probably print it on a printer with a resolution of 300dpi or higher.

Now to answer the POs question. As you can print larger prints at lower resolutions, the maximum print size in reality is VERY big! Large billboards are printed at very low resolutions but because you view them from a distance, they look fine.

That said, I'd aadvise speaking to your print lab and ask them what they require.

You are very correct sir. And, since you've highlighted the difference in your post between pixels and dots, allow me to expand upon the concept.

In the past I have been interested in pushing the limits in terms of enlargements. On my home printer (Epson R2400) this is usually the result of wanting to print an extreme crop as large as possible while maintaining very high quality. Ask anyone and they'll tell you that "fine art quality" is fairly universally recognized at 300ppi (note I say Ppi, not Dpi...I'm talking pixels here). (You may disagree--I've found very little difference between 240ppi and 300ppi myself, depending on the media and ink used.)

I've found, however, that on my R2400, 300ppi tended to make slightly worse prints when I'm pushing the limits than Canon printers. This didn't sit well with me because my Epson tended to outperform the equivalent Canon of the time in every other area--why would it fall short here? A little investigation revealed the truth to me. When setting a final print resolution, you *must* take into account the native printer resolution! If you don't, the printer driver must implicitly do another scaling in order to generate the image, sometimes manifesting as "jaggies" on near-horizontal and near-vertical lines, and which always results in a small loss in quality...very detectable when you've already done a lot of cropping and enlarging.

So what I discovered is this. The Canon printer's native resolution is 4800x1200, which is evenly divisible by 300ppi, so each image pixel is composed of a matrix of 16x4 printer dots. When printing at 300ppi, the printer driver need not do a final round of interpolation--each pixel is mapped to a 16x4 cluster of printer dots. Send the same image to my Epson, though, and 5760x1440 does not correspond nicely to a 300ppi image.

When scaling the image, however, if I choose 288ppi, I find I get better results from my Epson. I hit upon this by doing the simple math...at 288ppi, one pixel is printed by a cluster of printer dots exactly 20x5. At 300ppi, the Epson driver can't print each pixel directly without resizing. To make things even more difficult, I've found that if you print borderless prints, the print driver stretches your image slightly to fill the print. The exact amount of stretch involved depends upon a couple of factors and results in a tiny bit of the image being cropped off (for most printers, anyway)--the upshot is that once again the actual final resolution of the image is dropped slightly and the pixels no longer line up exactly with printer dots, which I've not figured out how to calculate yet.

In any case, a lot of people spend money on software like Genuine Fractals and then unnecessarily degrade the final print by choosing a resolution that must be scaled one final time in the print driver. If you don't make this mistake, you'll be surprised how much bigger you can go!

[blumesan]

Originally Posted by jbimages

There is a bit of basic maths that will help you work it all out.

Your camera's large image size is 3888 x 2592 pixels - at this stage they are just numbers. Each pixel is a point in the image and tells the colour and luminance at that point.

To print an image you need to put these pixels on paper. If you decide to stretch this out so that you have pixels 10 per inch you could create an image 66' 8" long and 21' 7" wide, but you probably need to fly over it in a plane or balloon to see what it is.
If you stood on it you would see a collection of multi coloured dots.


If you pushed the dots closer together so there were around 70-90 per inch you will have something close to what you see on the computer screen. It varies depending on the screen size and resolution (800 dots across a 15" screen are closer together than 800 dots across a 17" screen) (My 24" monitor at 1920 pixels is 80ppi)

The rest of your post was fine, and your subsequent post provided very good information; thanks. However the quoted text has me scratching my head regarding your "basic maths".

According to my maths, if I distribute 3888 pixels at 10 per inch they will cover 388.8 inches or 32' 5". And if you distribute those 3888 pixels at 80ppi on your computer screen, you would need a screen 48.6 inches wide to display the whole image.

Cheers/Mike

[westindiangal]

I printed 2 images to 20x30 from a Rebel XT and I'm very happy with the prints. I regularly use Mpix.

[jfrancho]

Use a good lab, like Mpix or WHCC, and send the image per their file specs and let them resize it with their RIP software. You'll be able to pretty much print whatever size you want, and it will look great at normal viewing distance. For example, a six foot print might not look so great at six inches, but who looks at a print that big from that close? I've made prints as large as 24x36 from my 8.2 MP camera with no issues. they are nice enough that I wouldn't hesitate to go larger.

[severoon]

I hesitate to post this link, but some may find it interesting: Resolution - Digicam - Andrew Gregory's Web Pages (could take a while to load).

The reason I hesitate to post it is that it gives all the mathematical formulas for calculating necessary resolution for a particular viewing distance, visual acuity, and visual acuity angle...which may or may not apply. Some studies have shown that prints made with a much higher resolution than is perceivable with the naked eye do in fact result in discernably higher quality prints. People were given a print at 240ppi and 600ppi in conditions that, according to their eyesight, ought to be indistinguishable. And from an objective standpoint they could not tell the difference in discerning specific details. However, when looking at the print as a whole, a statistically significant percentage of them were able to pick the 600ppi print as being higher quality, described with phrases such as "seems more dimensional".

So there is more to this than just pure numbers...I imagine that our brains process visual data in all sorts of ways of which we are not yet aware. I'm sure that there are very slight visual cues our brain keys in on to distinguish reality from flat reproductions, and the closer you can get to the physical actuality the better.