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Can anyone give me a quick lesson on dpi and printing. Is there any advantange to saving your files with 300dpi as opposed to 180 dpi. What is the advantage to taking photos on raw setting?

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Pam Teague

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It's generally accepted that the human eye cannot see individual dots or pixels in a photo at normal reading distance if there are at least 300 of them per inch. Therefore, to go above that figure would simply create a larger file with no visual benefit. So the figure of 300 pixels-per-inch for photo-quality printing became the norm. However, note I said "normal reading distance", and this is where you can get away with less than 300. If you are going to make a very large print (poster size) which is meant to be viewed from several feet away, your source image need only have 150-200 pixels-per-inch, because from several feet away we still would not be able to see the individual pixels in the printout. But for all 'normal' prints up to 8 x 10 inches, I never go below 300 ppi., and I save all my images as such.

Now for the RAW file format. many advanced cameras, and all digital SLRs, let you shoot and save as RAW. This produces larger files than a JPEG, but it's big advantage is that, using software, you can adjust every aspect of a RAW image just as though you had 'a second chance' at taking the shot with your camera. That's especially important if your camera sometimes gets the white balance wrong. Unless it's a RAW image, correcting the white balance afterwards is nigh impossible or at best extremely difficult. A RAW image is not processed inside the camera (the file just carries a record of your camera settings), whereas a jpeg file IS processed inside the camera, and a lot of that cannot be corrected easily if something was overdone or not set right on the camera at the time.

One last point about RAW. It's not compressed (that's why it creates a bigger file), but because it's not compressed that means no image colour data is being discarded. That's why (as well as the other reasons above) the pros and perfectionists use it. A jpeg, on the other hand, IS compressed. Colour-data is discarded to allow the compression to work. In many cases this damage can be seen on the photo if it's printed larger than snapshot size.

Last edited by pip22 on Feb 8th, 2006 at 08:42 PM

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I use QImage, which takes the guesswork out of it. It uses incredible algorithms to enlarge the image to the best size for your printer and does the final sharpening at the printing resolution. It does this during the printing so you don’t have to store the really large files required for printing.

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Mark Rogers
http://www.pbase.com/lila161
http://www.framedestination.com
http://framedestination.blogspot.com
D60, 550EX, 100mm/2.8, 28-105mm
100-300mm, 17-35mm, Epson 2200

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I have used Qimage in the past and was satisfied with the results

.. but more recently I have been printing from acdsee 8 .. and I’m very pleased …

Here are just a few of the options

Filters

Specifies the resampling filter to use when printing images. Click the drop-down list and select one of the following:

Box: displays considerable tiling or jaggies when you resize an image.

Triangle: produces good results for image reduction and enlargement, but displays sharp transition lines.

Bicubic: produces good results with photo-realistic images and with images that are irregular or complex. Uses interpolation to minimize the raggedness normally associated with image expansion.

Bell: smoothes the image.

B-Spline: produces smooth transitions, but may cause excessive blurring.

Lanczos: produces the sharpest images, but may also introduce some ringing artifacts.

Mitchell: produces smooth transitions when enlarging photo-realistic images. This filter is good compromise between the ringing effect of Lanczos and the blurring effect of other filters.


gamma correction

Applies gamma correction to the printed images.

Type a number from 0.10 to 3.00 in the Gamma value field to adjust the gamma of the image. Higher values make the image appear brighter, while lower values make the image appear darker.


Here are a few links

info about the recent updates to acdsee pro
http://www.bytecamera.com/digital-c...s-total-co.html

acdsee pro site > http://www.bytecamera.com/www.acdseepro.com

download trial copy of acdsee pro > http://www.acdsystems.com/products/acdseepro/index

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Best Regards
Paul

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