Tim Grey's DDQ Digital Darkroom Questions
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Today's Question:
In reading your explanation about using Fit Image to resize images for a slideshow in a recent DDQ email, I am wondering what happens to the natural ratio of height to width if you automatically set the pixel dimensions as you propose. I currently simply go to Image > Image Size and resample to 768 on the longest side (which is the requirement of our Camera Club digital competition). Because the cropped image often varies in ratio of sides, we get different pixel dimensions for the shorter side. Wouldn't the procedures you outlined cause an image's size to be distorted?
Tim's Answer:
This is an excellent question, because the risk of having the aspect ratio of an image changed during resizing is something I think any photographer should be concerned about. While it is possible to slightly change the aspect ratio without adversely affecting the image (and in fact, in some cases altering the aspect ratio can actually improve the aesthetics of the image), I recommend that the aspect ratio of the image be maintained in most cases.
When using the Image Size command, the Constrain Proportions checkbox is turned on by default, and thus the aspect ratio of the image will be preserved. If you change the Width, for example, the Height will adjust in proportion as long as the Constrain Proportions checkbox is turned on. I recommend leaving this checkbox turned on at all times (except in the rare case where changing the aspect ratio slightly provides a benefit).
When it comes to the Fit Image command, there isn't a checkbox for Constrain Proportions, but that is because the Fit Image command always maintains the aspect ratio of your image. The key to realize here is that the Fit Image command doesn't actually resize the image to the exact dimensions you specify, but rather resizes the image to fit within a box with dimensions you specify. So for a given collection of images that all have slightly different aspect ratios, if you set Fit Image to a Width of 1024 and a Height of 768, all vertical images will be 768 pixels tall, but their widths will vary. No distortion will occur.
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