Re: A couple newbie ?s re: Resizing and resolution
OK, let's take these one at a time: [quote="DanTheMan":2074g00g]1)Why would I use any resolution other than 300ppi (or even better if possible)? If file size is the issue, I have lots of HD space.[/quote:2074g00g] File size is seldom the issue here. The native resolutions of most inkjet printers is around 300 dpi (that's 'dots per inch', not the same thing as pixels per inch (ppi) but they are related). However, the native resolution of Epson printers is around 360 dpi, and converting to 360 ppi will generally yield better results on an Epson. So, generally speaking, 300 ppi works well for most printers, and 360 ppi works marginally better for Epsons. However, if you are making a very large (poster size or better) print, you can sometimes get away with less ppi. Why? Because the farther away your subject is from the print itself, the less resolution is needed to provide the illusion of continuous tone. And the larger the print, the farther the subject will naturally stand from it to view the image as a whole. Image content also plays a role- people will tend to stand farther away from a portrait, and move in on a cityscape to view the detail. there really is no magical formula- or if there is, I haven't found it yet. But I've printed large images at a resolution of 220 ppi and had them come out fine. By far the most general use of lowering resolution comes when the image is meant for web, not print. Anything meant to be viewed on-screen is generally reduced to around 72 ppi. Screens resolutions can vary anywhere between 72 ppi and a little over 100 ppi, but 72 ppi is considered the norm. [quote="DanTheMan":2074g00g]2)What happens if I just convert my RAW pics to JPGs and send them out to be printed; will they resize them at a low ppi?[/quote:2074g00g] That depends on your printer, and the size you're printing the images at. Your Nikon 8800, set to it's maximum image size, creates digital images that are 3264x2448 pixels. So let's assume you're not using an Epson. the printer's native rsolution is about 300 dpi. If you tell it to print an photo that is 10 inches by 8 inches, its going to convert hthe image to about 3000 pixels by 2400 pixels. I'd be amazed if you noticed the difference. But if you tell it you want a 6x4 print, it will convert the image to around 1800x1200 pixels. Now, if you're lucky, it will just discard the pixels it doesn't need to get to the image size it wants. In this case it would discard about every other pixel. The place where this will make the biggest difference in your photo is at the high-contrast edges. If you've done any sharpening, you've just cut the width of your halos in half, significantly softening the image. And that perfect six-pixel feathering on the object you imported into your image just became a 3-pixel feathering job. I would say that this is what happens about 80-90% of the time, and it is [i:2074g00g]definately[/i:2074g00g] noticable. In the worst case scenario, the computer will attempt to put all the detail of your image into the smaller version. the result of this is the opposite of the first result, the edges look blocky and over-pixelated. The solution for both of these conditions is simple: Decide ahead of time what size you want the print to be, and reduce the amount of pixels in the image to 300 times the size in inches- either by cropping the image, or by going to Image> Image Size to scale it down. Do this before you do any sharpening, so that the effects are not reduced along with the image. [quote="DanTheMan":2074g00g]3)If I resize most of these to 4x6 and a few 8x10s and change my mind and decide to make a few of the 4x6s larger, can I just open them and resize them, without loss, or do I have to go back to my original saved pic?[/quote:2074g00g] If you're letting the printer manipulate the images, then yes, just re-open the image and specify a different print size. The printer does not re-save the image after it changes its size, so you're essentially starting with the same file you had before. However, if you decide to take my advice, then you'll need a separate file for each print size you want. I've learned to code this into the filename. For example, "squirrel1(5x7).jpg". Does this make things more of a pain? Yes it does, no doubt about it. But once you get the hang of it, it takes about 45 seconds TOPS to change the image size, and the improvement in print quality is worth it to me. When you get the hang of this, let me know and we'll discuss the other part of creating a great print- sharpening. Hope this helps. -Medley.