Thursday, May 21, 2009

Tim Grey's DDQ - Image Size for Slide Shows

From Tim Grey...

Today's Question:

I'm doing a slide show and am going to use the Image Processor in Photoshop to reduce file size (all are large TIF's). The size of the projector outputs at 1024X768. So I think a height and width of 1200 by 1200 would be okay, correct? What should the quality setting be? An additional problem I have is that none of the files are sharpened, so I'm thinking of making an action to apply a mild sharpening to the 200 files. Having not done a slide show, I'm not sure how to proceed.

Tim's Answer:
Setting the images to fit within 1200x1200 pixel dimensions would certainly work fine, as they would then be resized (or you could resize them) within the context of the software you're using to produce your slideshow. However, there's really no need to have the images that large (not that they would be significantly larger than you need), particularly for vertical images. Using 1200x1200 would cause vertical images to be 1200 pixels tall, when your digital projector can only display 768 pixels tall. So I would use 1024 pixels for the Width and 768 pixels for the Height so all images will fit within the constraints of the digital projector you're actually using.

The Quality setting offers a tradeoff between file size and image quality. It is most important to consider for images you'll share online or via email, as the file size affects how long it takes for the image to download so the viewer can actually see the image. However, with a digital slideshow the file size isn't as critical. Therefore, I recommend setting the Quality to the maximum value of 12 when saving images as JPEG files for a digital slideshow.

As for sharpening, you can most definitely add this as part of the work conducted by Image Processor. You'll first need to record an action that applies the sharpening to your image. I recommend using Smart Sharpen for this purpose, as it is good about not creating sharpening artifacts and is thus safer to use when it comes to "blind" sharpening such as this. Once you have an action recorded that will apply sharpening, turn on the Run Action checkbox in section 4 of the Image Processor dialog box and choose the set and action you'd like to apply (the sharpening action in this case). That action will be applied to the images as they are processed by Image Processor.

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