THE FINAL RESOLUTION: DIGITAL PHOTOGRAPHY

Ever wonder why the printer refused to accept your digital photographs; or why your images look great on your monitor but lousy in your alpaca brochure? What's all this about DPI and Resolution?

People often get confused about the resolution (or dpi) of their images . After transferring the images from their camera to a computer, many open their files up in a program like Adobe Photoshop and then discover (under the "Image Size" menu) that the image is "only" 72 dpi, and begin to despair because they've been told that 300 dpi is photo quality, and 72 dpi is only screen quality.

Here's the scoop - dpi is a printing term, and is unrelated to the term "megapixels". Understanding the difference between the two is essential for creating images appropriate for your use, whether it be a printed piece or for use on your alpaca website.

Image 1 below is an example of a 6 megapixel image, as opened in Photoshop. The "Image Size" dialog box, shown on top of the image, is where you can view the particulars of the image. Notice that the pixel count confirms the megapixels (2000x3008 = just over 6 million pixels). Also note that the image resolution is shown as being 72 pixels per inch (ppi, or commonly misnamed dpi). But, also notice the dimensions of the image - 27.778 x 41.778 .

Now, if we make some adjustments you should start to understand how this whole "dpi" (or ppi) thing comes into play. And how you can take a 72 DPI, suitable for screen display, and convert it to 300 DPI, suitable for printing.

Image 1:

Example of a 6 megapixel image at a 72 pixels/inch resolution. Notice the overall pixel dimensions at the top of the "Image Size" dialog box. Also take note of the document size, shown here in inches.

In the image below, Image 2, notice that the "Resample Image" box has been deselected. Do this first before making changes to the resolution. Here the "Resolution" figure is changed from 72 to 300. Notice what has happened as a result - the printing dimension has gone down from 27.778 x41.778 inches to 6.667x10.027 inches (a bit over a 6x10" print size). However, you will see that the pixel count hasn't changed at all, and is still 2000x3008 pixels (6mp), and at the top of the image size box you can see that the image size of 17.7 megabytes has also remained unchanged.

Image 2:

The same image with the resolution changed to 300 ppi. The pixel dimensions at the top of the "Image Size" dialog box are as before, but the document size is smaller. Basically the computer rearranged the available pixels-crowding more per inch. Note: The "Resample Image" box was deselected prior to changing the resolution.


We didn't add or subtract pixels, as the pixel count and file size has remained the same. So, what happened? Well, all we've done is "rearranged" the pixels. By telling the software to adjust the printing resolution to 300 ppi, it crammed more pixels into an inch (increased from 72 to 300), which conversely reduced the printing dimension dramatically - from enormous poster size, to a bit over a 6x10" print size. In other words, by filling each inch with more pixels, the pixel count can't cover as many inches! It is like having 100 people standing one foot apart in a large room, then asking all 100 people to move to a much smaller room, while keeping their relative positions. You haven't lost anyone, and they're in the same order. But now, instead being a spacious foot apart, there's a mere inch between each person. 

So now you know how to manipulate and change the resolution of a digtal image. But how do you decide what DPI is appropriate? The determining factor in selecting DPI is your end use, or rather your means of display or reproduction. For instance, are you going to be printing your image in a high-end magazine? Or is it to be displayed on your website? Knowing the end use at the outset is critical for ensuring you produce images that will display and reproduce effectively.

High-end printing such as offset printing used for magazines, brochures and catalogs, requires images to have a resolution of 300 DPI, and possibly higher. When beginning to prepare your files for printing, it is a good practice to speak with your printer or production house to ascertain the appropriate resolution for your images.

Marketing vehicles in the digital arena, such as your web site and email campaigns, all require images at 72 DPI. There are a number of reasons for this, but the simple one is that computer monitors are only capable of displaying images at this resolution. Anything over 72 DPI is excessive and simply not used.

The scope of this article is to explain the basics of digital file properties, specifically resolution. Although we have only touched on the fundamentals of digital file manipulation and management, understanding these will help you enormously in your goal to create outstanding alpaca images usable in all your marketing.

For more information contact BreedWorks at info@breedworks.biz

Finally, I understand it. THANKS!! Anonymous, 12/12/07

Alpaca Marketing
Photography