G7 -- Max resolution question

[npish]

Hi, I just purchased a Powershot G7, and it seems when quality and image size settings are at max, the highest resolution produced is 180 dpi-- is this right?

I can't imagine that a $500 10 MP camera would only produce 180 dpi images at the highest settings....please tell me this isn't the case; and if not, what settings can I modify to achieve a higher resolution (i.e. 300 dpi) ?

Thanks for any assistance.

[David Metsky]

DPI listings from images mean nothing. That ONLY has relevance when you are printing, the number that PhotoShop tells you is essentially a random number with no use.

The only thing that matters is the dimensions in pixels of the image.

[Graystar]

You need to understand a little more about dpi, ppi, and resolutions.

The DPI value that is stored in the image has absolutely nothing to do with the image size or quality of the image. It is simply a printing directive...a suggestion, if you will...on how to print the image. It does not need to be followed and it rarely is. It is used most often by consumer home printers. In fact, I don?t think Canon cameras actually assign a value to their images. The value you see is the default value of the image editor you happen to be using. I've opened the same image with different software and the value changes.

There?s a difference between the dpi of an image and the dpi of a printer. For that reason, the dpi of the image is generally referred to as ppi (pixels per inch) and several image editors display this value as the ppi. A printer?s dpi value does not mate one-to-one with an image?s ppi value. Some printers need several dots to create the correct color of a single image pixel.

Commercial printers have an effective dpi resolution of about 1200 dpi but will print an image at (what is effectively) 250 pixels per inch. It doesn?t matter if your ppi setting is 180, 300, 50, or 36763492. That value is ignored. A typical commercial printer of standard sizes will simply take your image and scale the available pixels as necessary to print at 250 ppi at the selected size. The resizing process is done automatically by the printer software. Commercial printers actually print an oversized image (by 2% or so) to insure that the image fills the paper on borderless prints. This avoids getting bands of white at the edges. Roll paper will drift slightly as it runs through the printer, hence the need to oversize the image.

Your G7 has a resolution of 3648 x 2736. That means that you can print as large as 14.592? x 10.944? (standard size 11 x 14) with excellent detail. Smaller prints will actually be scaled down (resolution decreased) in order to print on 8 x 10 or 4 x 6 paper.

Larger prints will be scaled up. The quality of the resulting image is the subject of much debate on the internet. I personally have found that an image can be stretched out to 200 ppi and still print with very good detail. Others claim that they can see detail degradation at anything below 300 ppi (the 300 ppi prints having been made on high-end home printers or specialized commercial art printers.) As such, some people will scale up the resolution of the image themselves before sending the image to be printed.

So if you wanted to print on 16 x 20 paper you might want to scale your 3648 x 2736 image upwards to 5000 x 4000. There?s a lot of science and technique behind this process so do a search on ?uprezing? and be prepared to read a lot (don?t forget the salt.) Personally, I would just send the image as is (prints at around 180 ppi.)

Bottom line? My personal opinion is this...don?t worry about it. You can print up to 16 X 20 with good results without lifting a finger. Smaller prints will be stunning. Congrats on purchasing a great camera.
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Psr-s500 (http://www.yamaha-tech.com/wiki/Yamaha_PSR-S500)