Printing a 20D image at A3 or larger on Epson R1800

[siberia1997]

I have a Canon 20D. The maximum area resolution that the camera can produce in an image is 3504 x 2236 (approximately 8.2 million pixels) in either Large Fine JPG or in RAW.

I also have an Epson Stylus R1800. Epson recommends an image resolution of 200 - 300 dpi in its "Complete Guide to Digital Printing". According to its "Guide", one can determine the maximum print size possible from a digital image without any computer interpolation created by selecting the "Resample Image" box in their print driver if the area resolution of an image is known. For example, 200 dpi multiplied by each side of an 11" x 17' print would require an area resolution of 2200 x 3400 (determined by multiplying each side of the 11" x 17" print by the number of dots per inch - in this case, by 200).

The "Magic Lantern Guide" for the 20D claims that with the 20D, one can make great prints at 16" x 20" and more, but "only when the image is shot at 8.2 megapixels."

Even the user's guide for the 20D states that one can make A3 prints (which are approximately 11" x 17") or larger when the image is produced in either Large Fine JPG or in RAW.

I'm having a little trouble with the math. If I follow Epson's rule of thumb (and I assume that they know what they're talking about) and use an image resolution no smaller than 200 dpi, and I try to make a 13" x 19" print (which the Stylus R1800 is capable of printing), wouldn't I need an area resolution of 2600 x 3800 (200 x 13 and 200 x 19)? Since this is in excess of the area resolution of an image that the 20D can create (3504 x 2236), how can I make this print without asking the computer to do some image interpolation? If I do the math on the 16" x 20" image (if I had a printer that could print that sheet size), it's even worse: 3200 x 4000.

One thing that I haven't considered, nor have I even played with at all, is the RAW setting on the 20D. While the 20D's user's guide indicates that the number of pixels for a Large Fine JPG is the same as that of a RAW file (3504 x 2236, or approximately 8.2 million), the user's guide also indicates that the image file size (apparently different than the number of pixels) for a Large Fine JPG is approximately 3.6 MB, but is approximately 8.7 MB for a RAW file - quite a bit larger.

So, how does one print at 13" x 19" with an image taken from the 20D?

Can I only make the 13" x 19" print or large if the image was captured in the RAW format?

Does one have to print with an image resolution smaller than 200 dpi (meaning that the rule of thumb in Epson's "Complete Guide to Digital Printing" can be stretcI have a Canon 20D. The maximum area resolution that the camera can produce in an image is 3504 x 2236 (approximately 8.2 million pixels) in either Large Fine JPG or in RAW.

I also have an Epson Stylus R1800. Epson recommends an image resolution of 200 - 300 dpi in its "Complete Guide to Digital Printing". According to its "Guide", one can determine the maximum print size possible from a digital image without any computer interpolation created by selecting the "Resample Image" box in their print driver if the area resolution of an image is known. For example, 200 dpi multiplied by each side of an 11" x 17' print would require an area resolution of 2200 x 3400 (determined by multiplying each side of the 11" x 17" print by the number of dots per inch - in this case, by 200).

The "Magic Lantern Guide" for the 20D claims that with the 20D, one can make great prints at 16" x 20" and more, but "only when the image is shot at 8.2 megapixels."

Even the user's guide for the 20D states that one can make A3 prints (which are approximately 11" x 17") or larger when the image is produced in either Large Fine JPG or in RAW.

I'm having a little trouble with the math. If I follow Epson's rule of thumb (and I assume that they know what they're talking about) and use an image resolution no smaller than 200 dpi, and I try to make a 13" x 19" print (which the Stylus R1800 is capable of printing), wouldn't I need an area resolution of 2600 x 3800 (200 x 13 and 200 x 19)? Since this is in excess of the area resolution of an image that the 20D can create (3504 x 2236), how can I make this print without asking the computer to do some image interpolation? If I do the math on the 16" x 20" image (if I had a printer that could print that sheet size), it's even worse: 3200 x 4000.

One thing that I haven't considered, nor have I even played with at all, is the RAW setting on the 20D. While the 20D's user's guide indicates that the number of pixels for a Large Fine JPG is the same as that of a RAW file (3504 x 2236, or approximately 8.2 million), the user's guide also indicates that the image file size (apparently different than the number of pixels) for a Large Fine JPG is approximately 3.6 MB, but is approximately 8.7 MB for a RAW file - quite a bit larger.

So, how does one print at 13" x 19" with an image taken from the 20D?

Can I only make the 13" x 19" print or large if the image was captured in the RAW format?

Does one have to print with an image resolution smaller than 200 dpi (meaning that the rule of thumb in Epson's "Complete Guide to Digital Printing" can be stretched and still get great results)? The size claim that the Magic Lantern Guide makes ("...great prints at 16" x 20" and more), or even that of the 20D's user's guide ("A3 prints or larger"), seem to be so in excess of the print size when considering only the area resolution that the camera is capable of and the image resolution that Epson recommends that there must be something that I'm missing.

Can anybody help me? Thanks a lot (and sorry for all of the details). __________________ love God - love people

[mgbeach]

I'd say take the crop tool in Photoshop, set it at the required dimensions, set the PPI to 200. Drag out the bounding box, right click and hit crop. Print till your heart's content. I've had 20x30 prints made from my Digital Rebel (6.3 MP) that I did this way and they looked great. If you want to do it their way though, you'll get fine prints in the 100 -150 dpi range. Good luck!

[Hoopster]

Best to upsize images in small amounts (10% increments) to retain as much detail as possible. With the standard 20D file upsize by 110% say 4 or 5 times then crop to the required size.

[robertwgross]

You are mixing apples and oranges.

I have a Canon 20D. The maximum area resolution that the camera can produce in an image is 3504 x 2236 (approximately 8.2 million pixels) in either Large Fine JPG or in RAW.

I also have an Epson Stylus R1800. Epson recommends an image resolution of 200 - 300 dpi in its "Complete Guide to Digital Printing". According to its "Guide", one can determine the maximum print size possible from a digital image without any computer interpolation created by selecting the "Resample Image" box in their print driver if the area resolution of an image is known. For example, 200 dpi multiplied by each side of an 11" x 17' print would require an area resolution of 2200 x 3400 (determined by multiplying each side of the 11" x 17" print by the number of dots per inch - in this case, by 200).

The "Magic Lantern Guide" for the 20D claims that with the 20D, one can make great prints at 16" x 20" and more, but "only when the image is shot at 8.2 megapixels."

Even the user's guide for the 20D states that one can make A3 prints (which are approximately 11" x 17") or larger when the image is produced in either Large Fine JPG or in RAW.

Each statement has different degrees of accuracy. Here is the trick:
When somebody states that you want 300 DPI in a print, that is a very high standard, and it applies directly to small prints, like 4x6 inches. Maybe 8x10 inches. However, as you start to move up into larger and larger prints, the standard needs to slip down to 200 DPI or lower. Why? Because larger prints are viewed from farther back, so a decreased DPI is perfectly fine for a really huge print.

You can stay the closest to that high standard if you begin with the finest image file, which is RAW, and the best JPEG is about the same. Starting with a 20D image in RAW or the best JPEG, you can make prints to the limit of your printer without any problem. Note that if you try to print larger, your DPI will droop a bit, but that is OK.


One thing that I haven't considered, nor have I even played with at all, is the RAW setting on the 20D. While the 20D's user's guide indicates that the number of pixels for a Large Fine JPG is the same as that of a RAW file (3504 x 2236, or approximately 8.2 million), the user's guide also indicates that the image file size (apparently different than the number of pixels) for a Large Fine JPG is approximately 3.6 MB, but is approximately 8.7 MB for a RAW file - quite a bit larger.

Don't confuse the number of pixels with the size of the image file that displays that image. The RAW file (representing 8.2 megapixels) will be about 7-10 megabytes. The best JPEG file (representing the same thing) will be 3-4 megabytes. Why? Because the JPEG format is compressed. That means that it throws away tiny amounts of the image that it thinks (and hopes) is redundant or not very important. So, in some cases, the best JPEG will be a fairly close approximation of the original RAW file. In other cases, it is possible to go in and find the detail that has been lost from a JPEG, yet it was present in the RAW file. In other cases, the JPEG has discarded enough that you can actually see a big difference.

So, if you are anal-retentive (that is a hyphenated word, isn't it?), you will always stick to RAW for shooting. For some exceptions, you will drop to the very best JPEG, and that is as far as you'll go. For other people without the sharp eyesight, they won't see any difference. For eagle eyes, they will claim to see the difference.

So, don't get so hung up on DPI.

I printed one large print at 13x19 and got rave reviews. Due to the crop of the original image, the print was only about 150 DPI.

---Bob Gross---