A friend took one look at Easel and suggested that users would benefit from easy access to the online photo sites (e.g. kodakgallery shutterfly snapfish), where poster sized prints can be ordered at very reasonable cost (last time I checked, a 20x30 inch poster cost ~$20). This was an excellent suggestion and I took it. Although Easel has always been able to generate an image file that you could submit to one of these sites, I made several changes to make the process more straightforward and yield better results.
On the Page Setup window, the last entry on the list of available printers is Online Printer. When you select this, the list of available page sizes will expand to include all standard large formats, including all that I found offered at online photo sites in the US and the EU. Select the print size that you intend to have printed online.
In my experience, the online photo sites assume that you want a borderless print, so that even if you submit an image with borders, they are likely to enlarge and reposition it until the full page is covered. This means that if the area inside the margins does not have the exact same aspect ratio as the page itself, the print you get back will be missing part of the image along one edge.
The easiest way to avoid this problem is to set the margins to zero. However, you may find (as I do) that it's a little easier to compose an image when there is some white space around the edges, i.e. margins are not set to zero. Keep in mind, however, that unless the page size you are using is a perfect square (very unlikely), setting equal margins will change the image's aspect ratio. For example, if you set 1/2" margins on a landscape-oriented 20"x30" page, the image becomes 19"x29" and the aspect ratio changes from 1.5 to 1.53. This may not sound like much, but it will result in a 20" x 30 1/2" image. That 1/2" will be chopped off along the short edge of the print, and believe me, people will notice.
To avoid this problem, you need to set margins with the same ratio as the page so that you shrink the longer dimension more than the shorter dimension. For a landscape 20x30, 3/4" for left and right and 1/2" for top and bottom would work, as would 3/8" L/R and 1/4" T/B, and any other pair of measurements with a ratio of 1.5:1
When Online Printer is selected, commanding Easel to Print brings up the Create Image... window with a slider control to specify the resolution (in dots-per-inch, or DPI) of the image to be created. Underneath the slider is a color bar dividing the range into blue, green, and red zones, which will vary in proportion depending on the native resolution of the images in your composition and the size of the page. If all of your images are high res and/or you've chosen a small page, for example, there probably won't be a blue zone.
Settings in the blue zone, corresponding to resolution of 90 or fewer DPI, will create an image without sufficient resolution to create a good print of the size you want. If the whole range is blue, you will either have to settle for a lousy print or exit printing and shrink the page a size or two, because your images are too grainy to be blown up to the current size and still look good.
Settings in the red zone are overkill; they won't hurt the quality of the print, but they produce a bloated file that in most cases won't look any better than a smaller one. Increasing resolution beyond 300 DPI is usually going to be a waste of bytes and bandwidth.
So the green zone is generally where you want to be, though you should still check to make sure that resolution is 150-300 DPI. If you want to know more, such as why settings in the green zone don't guarantee this, read More on Resolution below.
If the current composition has margins set greater than zero, there will be an Include Margins check box underneath the color bar, checked by default. If you leave it checked, Easel will create an image that a) has corresponding white borders around it, and b) is guaranteed to have the same aspect ratio as the page size. If you uncheck it, Easel will create an image corresponding to the area within the borders with whatever aspect ratio it happens to be. If you have margins set only for ease of composition and have maintained the proper aspect (see Step 2 above), you should uncheck this box. Note that if you have margins set because you want margins in the print, be warned that the online photo site may ignore them.
Easel can save images in any of the formats supported by Windows' "Graphics Device Interface," though unless you have a good reason not to, you should stick with JPEG, which is what most online photo sites expect.
When JPEG is selected, you will also be presented with a JPEG Quality setting. This determines the amount of compression used by the JPEG algorithm to store the image. As quality goes down, file size shrinks dramatically, even though it's hard to see much visible difference at levels of 70 or more. I tend to use 80-85, just to be on the safe side.
When you have set resolution, margins, and format as desired, click OK to create the image.
Once Easel has generated the image file, all you need to do is upload it to the online site just as you would any other image file on your computer.
Note: Some sites have an "Upload in High Resolution" (or words to that effect) option to select when uploading an image for a large format print like a poster. Be sure to select this when uploading -- if you don't, the site may undo all your hard work and shrink the file to the resolution needed for a 4x6 print!
That pretty much covers what you need to know to prepare images for printing online. However, if you'd like to know more about the choices and graphics on the Create Image... window, read on.
Why doesn't Easel just let you select among standard resolutions? Why the color zones? Why do they shift around? And what are those funny gray boxes that appear in the preview as you increase DPI?
An Easel composition is made up of multiple images, and even if they all start out with the same resolution (e.g. taken by the same digital camera at the same settings), the resizing and cropping that goes on during composition means that they end up different; some a little, some a lot. In this sample 13"x19" composition, for example, the resolutions range from a low of 80 DPI, where I took a very small portion of an image and blew it up, to almost 700 DPI, where I used most of the image but kept it small. The average (mean) resolution for the 62 images is 380 DPI. What is the best way to deal with this kind of variation?
After giving it some thought, I decided that the best way was to make the information available to help you -- the user -- make an informed decision. Therefore:
The low end of the DPI range available with the slider control is whichever is less, 90 or the lowest DPI in the composition. 90 DPI, the minimal acceptable resolution for an online print, is the upper end of the blue zone. Thus if all images have resolution greater than 90 DPI, there will be no blue zone. If some images have resolution less than 90 DPI, the blue zone will extend from the lowest resolution up to 90; for the sample, it runs from 80 to 90 and is barely visible.
The top end of the DPI range available with the slider control is the highest DPI image in the composition. If all images in the composition were 90 DPI or less, the whole range would fall in the blue zone, a suggestion that you need to downsize the print. For our sample, however, the top end will be set at 680 DPI. As noted above, you generally wouldn't want to use such a high value for an online print, but it makes sense to make available the highest resolution in the underlying images.
Finally, the green zone. The green zone runs from 90 DPI up to the average resolution of all images in the composition; for the sample, 380 DPI. The logic for this endpoint is that there is no point in creating an image in which a majority of the images have been interpolated, i.e. blown up beyond their native resolution and filled in. There's no intrinsic problem with interpolation, and it makes sense to interpolate a few images in order to match the higher resolution of others, but there's no point in doing it to most of the images, especially since the online photo sites will interpolate for you up to the limits of their equipment.
What about those grey boxes that show up in the in preview as you request increased resolution? They show which images in your composition have lower resolution than what you're asking for, and the darker they are, the bigger the gap. Thus they provide an "interpolation map" to help you arrive at an optimal setting for any particular composition.