Goleta DeskTop Publishing User Group
Meeting Information

April 4 -- Preparing Pictures for Viewing

The overall goal of taking pictures is to show them to someone, even if it's yourself. And you'd like the pictures to be worth looking at! Tonight's meeting will focus on how to massage the picture you've taken and prepare it for viewing.

These are the basic steps of preparing any photographic image, and are exactly the same as they were with wet chemistry and darkrooms:
 • Crop
 • Size
 • Adjust Brightness and Contrast
 • Adjust Color
 • Fix Flaws (red eye, etc.)
 • Sharpen
 • Save
 • Publish

Crop
You crop the image if you want to drop out extraneous stuff that is peripheral to the subject of the picture. The amount of cropping you can do is limited by the amount you want to magnify the cropped image, which gets us to the next step.

Size
The picture needs to be sized for the target "medium", even if that medium isn't physical. For instance, if you are going to send the picture as an email attachment, you will probably want to limit the size to no more than 720 pixels wide and 480 pixels high, because that size image is about the largest that can be viewed on an 800 by 600 pixel screen without having to scroll around. That same size is also appropriate for a web page that consists of only that picture.

However, if you want a print you will need about 240 pixels per inch of the print, so a 4" by 6" print needs an image of about 960 pixels by 1440 pixels. Much less than that and the print starts looking soft, which is fine for clouds and other amorphous items but not for images that have a lot of crisp detail. If you want an 8" by 10" you'll need an image of about 1920 pixels by 2400 pixels. This is a lot bigger than what you'd put on a web page or send as an email!

One of the problems with making a large paper print is having enough pixels for a sharp image. If the picture is from a 2 megapixel camera you just don't have enough information for a tack-sharp 8x10. Resizing an image to generate more pixels really doesn't help because all it does is make more pixels, not more information (otherwise known as detail). This is the reason you can't do much (if any) cropping on a picture that has only a few megapixels if you want to make a large crisp paper print.

Adjust Brightness & Contrast
Now it's time to adjust the brightness and contrast. Generally speaking you want to avoid the controls that have those names -- there are better ways of doing it! Basically, you want to set three points: the white point, the black point, and the midtone. The brightness and contrast controls don't let you do this as accurately or with as much ease as using controls that let you choose these points directly.

Adjust Color
Now that the picture is approximately right it is time to make any needed corrections to color. For instance, if you have a photo that was taken with a flash it often has a bluish cast and people's faces look a little off. This gets a little tricky when the picture was taken in daylight with a fill flash because most of the picture's color looks right, but those shadow areas that were illuminated with the flash will be too blue. And unfortunately, commonly one of those shadow areas happens to be the subject's face, whose skin tone now looks cyanotic.

Fix Flaws
The picture should be looking pretty good now, so it's time to fix the remaining few flaws, like red-eye, the blotches on the wall, and other things that are yelling for attention and distracting the viewer from looking at what you wanted them to see.

Sharpen
The final step is to sharpen the image. The process of resizing and manipulating an image softens it, and with a little judicious use of the "unsharp mask" you can get back much of the sense of sharpness. You do have to be careful that you don't over-sharpen, because then everything has halos around it and looks quite unnatural.

Save
We have several choices about how to save the picture. I usually like to save it both in the photo manipulation program's native format so I can make further changes later, as well as in the file format needed to "publish" it.

Publish
The final step is publishing the picture. If you are putting it on a web page or sending it with email, the best file format is usually JPEG. If you are going to make a print either a high-quality JPEG or TIFF is usually preferred. If you are sending the file to someone else to print you should ask them what they want.

Please send email to gdtpug@troutcom.com with suggestions for topics you are interested in seeing covered. Or even better, volunteer to give a presentation!

The Goleta DeskTop Publishing Users Group is a SIG (Special Interest Group) of the Santa Barbara PC Users Group. We are not platform specific: some members have PCs, some have Macs, some have both. Linux and other systems are sprinkled in as well for good measure. We focus on the issues of publishing in all forms, be it on paper, web, CD-ROM, or some other medium.