a quarterly online publication from

The Digital Photo Issue

Vol. 2 No. 2, April 2005
http://www.kauaidesign.com

I. De-mystifying Resolution

II. "Photo Quality" Printing

III. Adding Type to Photos

IV. Glossary of Photo File Formats

V. Back Issues

VI. Do You Want to Receive THE GRAPHICS GRAPEVINE?

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I. De-mystifying Resolution

pixel: smallest unit of measurement in a digital image. Pixels are typically square and make up a grid the height and width of your image. Measured in microns (1/1000 of a millimeter or about 1/25,000 inch). Image sensors in most consumer cameras have pixels 4 to 5 microns square.

ppi: pixels per inch. How resolution is measured for your "capture" or "input" devices (camera, scanner) and your computer monitor.

dpi: dots per inch. How resolution is measured for your home/office printer which outputs your image in round dots, not square pixels.

lpi: lines per inch. How resolution is measured for offset presses. Newspapers generally print at 100 lpi and require 200 ppi images for quality reproduction. Magazines use a 150 lpi linescreen (300 dpi images) and art books and exhibition prints are printed at 200 lpi (400 ppi images). The rule of thumb is to print images at a dpi that's double the lpi.

megapixel: one million pixels. How the resolution of digital cameras is measured. The larger the megapixel rating, the more information you can capture within an image and the larger you can print that image, maintaining high quality.

resolution: level of detail attainable by a monitor or a printer, determined by the ppi, dpi or lpi. When capturing images for printing, the higher the resolution, the greater the detail (up to a point) and the larger the file size. Quality may also be affected by the lens capturing the image, the camera's ability to process the image, and the grain and size of a scanned original.

pixelization: the jagged stairstep effect you see on a low resolution image printed larger than optimal for its file size.

file size: how many kilobytes (k) or megabytes (mb) of information in a file. Determined by the resolution and physical size of an image. Relevant for screen display and printing of images as well as storing and transferring of files.

compression: how much of the potential information in an image file is discarded for the sake of keeping file size down. Saving a photo in .jpg format allows you to choose a compression level, depending on whether better quality image or smaller file size is more important for your purposes.

II. "Photo Quality" Printing

A fairly standard output resolution for "photo quality" digital printing is 300 dpi. However, if the image is not too finely detailed, if it will be printed on low quality paper such as newsprint, or if it wiill be viewed from a distance, you may be able to get away with a dpi as low as 200.

You can always resample down (from more resolution to less) but you typically lose image quality by interpolating up. So if you're shooting for print, capture at the highest quality your camera settings allow: High, Best, Fine, or whatever your system calls it. This setting will capture the image using the lowest compression ratio or no compression at all. Shooting at highest quality may also give you the flexibility to crop and enlarge a portion of your image later and still maintain photo quality resolution. You won't get as many images on your camera's memory card shooting at high-res but you can keep your creative options open by archiving your "keepers" on CD. Your future self will thank you.

The following formula can help you calculate:

1) how large a print you can make from a digital image with a given set of pixel dimensions and a given resolution (ppi)?

2) what resolution a digital print will have printed at given output dimensions from a file with given pixel dimensions

3) what dimensions in pixels your digital image will have captured at given dimensions in inches and at a given resolution

(whew!)

EXAMPLE If you know the print resolution required for a printer (say 300 dpi) and you know the desired output size (make it 5 x 7") you can multiply the two for the pixel dimensions. 5 x 300 = 1500. 7 x 300 = 2100. Pixel dimensions = 1500 x 2100 or 3,150,000 pixels. You would need a 3 megapixel camera to capture an image of this physical (output) size at this resolution.

III. Adding Type to Photos

In graphic design, words and pictures are often combined to make a statement. Captions can be placed under an image to tell the story. But adding words to the image itself can be more impactful. However, It's important to keep the type legible when doing this. Here are some ways to make your type stand out:

Use bold fonts without serifs or fussy detail.
Choose color(s) that contrast with the background.
Place text on part of the image that is low in contrast and not too busy.
Add black and/or white shadows to type to set it off from the background and add depth.
Or add a thin outline in a contrasting color to type to define its edges.
Screen back or "ghost" the photo so dark type stands out against it. (See below.)

Bold font in contrasting color on uncluttered background Black and white shadowing with ghosted background image

In page layout, image editing, or drawing programs, it's simple to overlay text on a graphic. In Microsoft Word 2000, you can follow these steps:

1. Insert your photo into a document by selecting the Insert tab and clicking on Picture. Click on From File and navigate to where the image is stored on your hard drive, CD or other storage device. Click on the image and it will insert into your document. Re-size if desired.

2. With the photo selected go to the Format tab and select Picture on the dropdown menu. Here you can crop the image and adjust brightness and contrast if desired. Adding brightness and reducing contrast will give you a ghosted version of your image over which you can place dark type for good legibility. You can also convert your original color photo to grayscale, black and white, or a watermark using the Color options on the Picture tab.

3. On the Layout tab, choose Behind Text as your wrapping style. Uncheck the Move Object With Text box in the Advanced settings on the Layout tab while placing your text.

4. Now you can place your cursor on top of the photo and type your text.

5. To color text, highlight it and click the "A" icon on the Drawing toolbar to choose from a palette of colors. If the drawing toolbar is hidden, go to the View menu, select Toolbars from the dropdown menu, then Drawing.

6. Word Art can also be added to an image by selecting the Insert tab, then Picture, then clicking Word Art. You can choose from the Word Art "gallery" options, some of which have built-in shadows or outlines, or you can create your own text from the various shapes, colors, sizes, angles, and letter spacing options in the Word Art toolbar. To activate this toolbar go to View menu / Toolbars / Word Art.

BMP The bit-mapped file format used by Microsoft Windows. The BMP format supports RGB, indexed-color, grayscale, and Bitmap color modes.

EPS Abbreviation for Encapsulated PostScript. File format capable of containing both high-quality vector and bitmap graphics, including flexible font capabilities. The EPS format is supported by most graphic, illustration, and page-layout programs.

JPEG Abbreviation for Joint Photographic Experts Group. JPEG is an image file format with various compression levels. The higher the compression rate, the lower the image quality, when the film is expanded (restored). Although there is a form of JPEG that employs lossless compression, the most commonly used forms of JPEG employ lossy compression algorithms which discard varying amounts of the original image data in order to reduce file storage size.

Editor's note: JPEG has become quite popular and is the default format for most digital cameras. While its small file size allows you to capture a lot of images on a memory card, its "lossy" compression makes it less than ideal for image editing. Every time you save the file, the picture quality degrades. Multiple saves can result in a noticeable loss of quality. If you lighten the photo one day, crop it the next day, then go back and add more contrast, the photo has been saved at least three times, and will not be as clear and crisp as the original. Once the photo quality has been lost, the original quality cannot be restored. To avoid this degradation issue, save your JPEG photos to a CD or other storage system as TIFF files. You can do this with most photo software, or with Windows XP. (Open the image. From the File menu, choose Save As. In the Save as type box, select TIF. Compression option None is recommended.)

PSD Adobe® Photoshop® file format (PSD) is the default file format and the only format that supports all Photoshop features. When saving a PSD file for use in a previous version of Photoshop or ImageReady, you can set a preference to maximize file compatibility.

TIFF Abbreviation for Tagged Image File Format. File format commonly used for image files. 8-bit RGB TIFF and 16-bit RGB TIFF are two variations that most image editing software applications recognize. RGB TIFF is a common choice for saving images after they have been adjusted for size, cropping, color, contrast, sharpening, etc. in editing software such as Adobe® Photoshop®. Always convert to CMYK color mode for printing.

V. Back Issues

If you missed previous editions of The Graphics Grapevine, and would like complimentary back issues e-mailed to you, please write to linda@kauaidesign.com

Vol. 1 No. 1, January 2004: I. What IS Graphic Design? II. The Good, the Bad and the Ugly III. Your Graphic Identity IV. Why Choose Print?

Vol. 1 No. 2, April, 2004: I. Postcard Promotions II. Type Tips: One Space Betweeen Sentences III. Type Tips: Underlining IV. White Space

Vol. 1 No. 3, July 2004: I. Making Headlines II. Type Talk III. Break Up Text With Graphic Elements IV. The Mission of Kaua`i Design Graphics

Vol. 1 No. 4, October 2004: The COLOR issue: I. A Color Wheel Refresher Course II. The Impacts of Color III. RGB and CMYK Color

Vol. 2 No. 1, January 2005: I. One- and Two-Color Printing II. Proofreading: Tools of the Trade III. Type Families IV. Calling All Questions!

VI. Do You Want to ReceiveThe Graphics Grapevine?

Future editions of The Graphics Grapevine will be sent to you by e-mail each quarter only if you want to receive them. If, for any reason, you’d like to remove your name from the e-mail list or add your name to the list, please e-mail: linda@kauaidesign.com

Owner of Kaua'i-based Kaua`i Design Graphics, Linda Pizzitola specializes in logos, business identity packages and print promotions. Kaua'i Designcollaborates with business owners and event promoters to bring their graphic identities to life. See samples of her work, a client list and more at http://www.kauaidesign.com. Linda can be reached by phone at (808) 822-0055.

In the TWO HEADS ARE BETTER THAN ONE Department, thanks to Tom Niblick at Printmaker, Kauai's digital printing studio, for his professional review of the above information.