Creating Compelling Still Images from Digital Video

This chapter is from the book

Sams Teach Yourself Digital Video and DVD Authoring All in One

Learn More Buy

This chapter is from the book

This chapter is from the book 

Sams Teach Yourself Digital Video and DVD Authoring All in One

Learn More Buy

Importing and Scanning Images

Getting your digital images onto your hard drive is relatively easy. Scanning in photos takes a little more effort. In the latter case, you want to streamline the process (because scanning is time-consuming and tedious) to ensure you have a consistent look and to avoid last-minute fixes when editing them into a video or DVD.

Importing Digital Images to Your PC

Your digital camera probably came bundled with some image-capturing and editing software. But if that's not the case, you don't need commercial software to load digital images to your PC.

When you connect your camera to the PC (typically using an included USB cable) Windows detects that connection and then displays a window labeled Removable Disk (Windows considers your camera to be a storage device, like a hard drive). Select Copy Pictures to a Folder on My Computer and click OK to open the Scanner and Camera Wizard as shown in Figure 3.10.

FIGURE 3.10 When you connect and turn on your digital camera, Windows pops up this Removable Disk screen.

Within the Scanner and Camera Wizard (shown in Figure 3.11), you can select photos you want to use in your project. After making your selections, click Next, select a file folder, and save the photos. At some point you might want to crop them or do some touch-up work. I give a brief overview of both techniques later in this chapter.

FIGURE 3.11 Use the Scanner and Camera Wizard to select "keeper" photos to store on your hard drive.

Selecting a Scanner for Your Video and DVD Projects

A scanner is a critical part of your video and DVD production toolset. You will frequently need to include printed photos, logos, graphics, or other hard copy in your projects. To do that, you need a scanner.

Now is a great time to buy either your first scanner or one to replace that old clunker in the corner. For $75–$150 you can get plenty of horsepower.

Scanner Buying Tips

Before heading off to the store or jumping online, take a look at the following shopping tips:

• Dots per inch (DPI) and color depth—1,200dpi is sufficient for video production work; 2,400dpi works well for high-end photo or prepress projects. 42- or 48-bit color depth is more than you'll ever use. Most image-editing software scales down to 24 bits—8 bits per color (red, green, and blue).

Which Way Is Up?

DPI is supposed to be noted as horizontal by vertical, as in 1,200x2,400. The horizontal number is the true resolution and refers to the density of sensors in the image chip. The vertical number equals the steps per inch that the scanner motor moves the scanner head. Some manufacturers flip the numbers, so pay close attention.

• CCD versus CIS—Most scanners use CCDs, the same type of image sensor chips found in digital still and video cameras. At least one company—Canon—relies on contact image sensor (CIS) chips. CIS chips use less power and are more compact (making for some very trim and sleek scanner designs). However, they have trouble with books that don't lie absolutely flat on the scanner glass, they are slower than the norm, and they can't do transparencies. So stick with the industry-standard CCD scanners.

• Scanning speed—This varies greatly and changes with each new model. I suggest checking online at CNET or (reviews.cnet.com) or PC World (http://www.pcworld.com) for current bench test results. At last word Epson, HP, and Visioneer have the best scanning speeds for low-resolution (300dpi) scans—typically about 20 seconds.

• Connection speed—USB 2.0 scanners are becoming more popular (versus USB 1.1 or parallel connectors). If you have USB 2.0 capability, you will see speed improvements, but only for higher-resolution images. Otherwise, USB 1.1 is adequate.

• Transparencies—Most consumer scanners do not handle slides or negatives as a standard feature. You'll need an optional tray, which typically costs about $25.

• Onboard buttons—Some scanners give you several controls on the scanner itself, which can be convenient and helpful.

• Bundled software—Most flatbed scanners come with the excellent ABBYY FineReader optical character recognition (OCR) software and a barebones image-editing package. Even though all scanners these days are TWAIN compliant, meaning that products such as Microsoft Word and Photoshop can directly access and operate your scanner, the software bundle usually includes a rudimentary scanner control interface.

Explaining Scanner Settings

If you already have a scanner you probably don't give much thought to its settings. I'm guessing you select a standard mode—print, photo, web, file—click scan, and that is that.

What you generally end up with (depending on the original document size) is a fairly large file, perhaps 2,400x1,800 pixels or more.

The thing is, images used for video productions don't need to be anywhere near that size. Standard NTSC TV sets can't display more than 720x540 pixels.

In addition, you probably scan at a high resolution—600dpi (dots per inch) or more. The reason: Standard inkjet printers work at 600dpi or more and you want your printed photos to look sharp.

However, TV sets display only at 72dpi (PC monitors typically have a slightly sharper display: 96dpi). In general then, there is no reason to scan at a resolution greater than 72dpi. The exception is when you are scanning a photo smaller than 5''x7'' (I'll explain the math behind that in a moment). The goal is to have even small images fill the TV screen and have them look sharp.

Using a dpi density much larger than 72 is a waste of hard drive space and time. The smaller the resolution, the faster the scanning process.

Scanning Images Using Manual Settings

Today's scanner software leans toward "idiot proof" status. That's not a good thing, because it gives you virtually no direct control over individual scans.

It's not the end of the world if you opt for the automated approach. But for consistent results, faster scanning, and smaller files, you might as well take a stab at the manual approach using Windows XP's built-in manual scanning option.

Before tackling this book's first Try It Yourself task, though, you need to do some calculating.

Selecting an Appropriate DPI

For consistent results, adjust your scanner's dpi setting based on the size of the image you're going to scan. In general, you set higher dpi settings for smaller images (less than 5''x7'') to ensure they display cleanly on a TV set. You can set lower dpi settings for larger images.

The goal is to create an image with 72dpi or more (but not too much more) to ensure sharp reproduction on your TV while minimizing file size and speeding up the scanning process.

Calculating Correct Scanner DPI

Photos generally are either vertical format (portrait) or horizontal (landscape). Horizontal matches the general shape of a TV screen but usually does not exactly match the aspect ratio. Photos tend to be a bit wider.

The goal is to have horizontal-format photos fill the TV screen from left to right. That means the top and bottom will not quite reach the top and bottom of the TV screen, but you can fill those gaps with a color background.

With vertical format pictures, your goal is to have the top and bottom of the photo touch the top and bottom of the TV screen. That means the left and right sides will be well inside from the edges of the TV screen.

Table 3.1 gives you some general dpi settings for photos of various sizes.

In general, smaller photos require higher dpi settings and larger photos require smaller dpi settings. But, as listed in Table 3.1, never scan at less than 72dpi because your image will lose fidelity. And it's always a safe bet to round up your dpi numbers—that is, calculate the proper dpi and then round it up to a slightly higher, even number.

Again, this isn't rocket science. The purpose simply is to have consistent-looking images, faster scans, and smaller file sizes.

Table 3.1 Scanner DPI Setting Examples for Photos (NTSC)

The Math Behind the DPI Settings

This section goes over the math behind how I arrived at the recommended scanner dpi settings. Feel free to skip it.

This is a two-part calculation that depends on your country's TV standard (NTSC or PAL), whether you're working in full-screen (4:3 aspect ratio) or wide-screen (anamorphic 16:9), whether you want to compensate for NTSC overscan, and the size of the document or photo.

Overscan is an NTSC issue (PAL and the other TV standard, SECAM, do not overscan). Most consumer NTSC TV sets enlarge the TV signal, pushing it beyond the edges of the TV tube. That means you frequently cannot see about 10% of the original video. For example, when watching CNN Headline News, you might not be able to read all the stock ticker data at the bottom of the screen.

If you're creating an image to play on a standard NTSC TV, you can ensure that viewers will see the image in its entirety—top to bottom or left to right—if you create your image using the overscan resolution noted in Table 3.1: 650x490 pixels (this is an approximation—overscan varies from TV set to TV set). You will later place that image within a 720x540 frame. In that way, overscan will cover part or all of the frame, but not the image.

You certainly can use the full resolution (720x540 pixels), but the edges of your image will not display on most NTSC TV sets. Figure 3.12 shows the approximate overscan area and the visible area, or the so-called safe zone.

To compensate for these differences and ensure that your images retain their original aspect ratios, you should create graphics using the resolutions noted in Table 3.2.

FIGURE 3.12 When working with NTSC DVD projects, you should keep images within the safe zone to compensate for overscan.

Table 3.2 Standard Image Resolutions—Sizes

Calculating the DPI Setting

For horizontal format photos, measure the width in inches and divide that into 650 pixels (the screen width compensating for overscan) for NTSC or 768 for PAL.

For example, with a 5''x7''photo, divide 7 into 650 to get 93dpi. When you scan a 5''x7'' horizontal format photo, select a dpi setting of 93 or slightly more.

If you have a 5''x7'' vertical format photo, you should divide 7 inches into the screen height, or 490. In this case, 490/7 = 70. That's less than 72dpi, so select at least 72dpi when you scan a 5''x7'' vertical format photo.

Use the Windows Scanner Wizard to Customize Scan Settings

With Windows XP, you have at least one built-in manual scanning option, no matter how your scanner's bundled software works. In this book's first of many Try It Yourself tasks, you will use a Windows Wizard's manually adjustable settings to create manageable-sized images. Here's how it works:

1. You might find the Scanner or Camera Wizard under Start, Programs, Accessories. If so, start it that way; if not, locate it in your Control Panel. You might have a Control Panel icon on your desktop, or you can find Control Panel under Start, Settings. In either case, open Control Panel, double-click Scanners and Cameras, and double-click your scanner's name in that window (you might then need to double-click Printers and Other Hardware to find your scanner). The Scanner and Camera Wizard shown in Figure 3.13 opens.

FIGURE 3.13 Use the Scanner and Camera Wizard to manually alter your scanner's settings.

2. Click Next, and you'll see the Choose Scanning Preferences screen shown in Figure 3.14.

FIGURE 3.14 Select Custom settings to adjust the dpi setting.

3. Select Custom settings to open the Properties interface. Here you select a dpi setting to match your image size. If it's a 4''x6'' horizontal format photo, select 109dpi, as shown in Figure 3.15. Click OK to return to the Scanning Preferences interface.

FIGURE 3.15 Use Windows XP's Scanner Wizard Custom setting to select a specific dpi resolution.

4. If you need to do any cropping of your image, now is the time to do it. Click Preview (it might take about a minute for the scanner to make a preview image) to display your image in the cropping window, shown in Figure 3.16. Drag the highlighted box corners to the desired size, and then click Next.

FIGURE 3.16 Crop your image before completing the scan to get the best results later.

Get Your Crops in Early

You should crop now rather than use image-editing software to do it after you've scanned your image. Doing it now ensures your image will have the proper dpi resolution, whereas cropping it later will lead to a lower-quality image because of reduced dpi (after you blow up the smaller cropped image to fill the TV screen).

You should also cut out large borders like those shown in Figure 3.16 and remove unwanted portions of the photo to save a cropping step later. If you plan to crop, don't include the cropped-out area in the measurement used to calculate dpi.

5. Click Next to open the Picture Name and Destination window shown in Figure 3.17. Name the picture, select a file folder, and choose an image type.

Selecting an Image Format

BMP and TIFF are the best of the four image formats available in the Windows Scanner Wizard because they are uncompressed and retain all image quality. PNG does compress image data, but it only imperceptibly alters its quality. Do not use JPEG because it both compresses and reduces image quality. In any event, most video-editing and DVD-authoring products can handle any of these four image types.

6. Click Next to make the scan and store the image. It's now available for further editing.

FIGURE 3.17 Select any of the four image formats—BMP and TIFF work best. The video-editing and DVD-authoring software covered in this book can handle all or most of them.