Frequently Asked Questions

Here are answers to some frequently asked questions that you may find informative.

Q: What is TWAIN?

A: TWAIN is an industry standard device specification that allows scanners, digital cameras and other image input devices to be attached to your computer. If the device is TWAIN compatible, your computer will be able to accept photos from it, provided you have TWAIN-compliant software and hardware.

Q: What is a digital image?

A: Digital images, or bitmaps, are composed of rows and columns of small pixels. Each pixel is assigned a color and shade which, when taken together, form the entire image. The number of pixels vary according to the size and resolution of the image.

Q: What is meant by ‘resolution?’

A: When referring to digital images, resolution is the number of pixels that make up the image, measured as width and height. The more pixels for a given sized image, the higher the resolution. Higher resolutions offer greater clarity, while lower resolutions take up less disk space. Some common resolutions are 320 x 240, 800 x 600, and 1280 x 1024.

When referring to your monitor screen, the same concept applies. Monitors are controlled by your computer’s video card. Video cards with more memory are able to display higher resolutions and more colors. Some common video resolutions are 640 x 480, 800 x 600, 1024 x 768, and higher, at up to 16.7 million colors. MGI PhotoSuite II requires your system to operate at 800 x 600, and 65,000 colors.

Q: Scanners and digital cameras offer me a choice of resolutions. Is it always best to scan or take digital photos at high resolution?

A: Not always. Lower resolutions are usually satisfactory if the image will be used primarily for monitor display, and to shorten transfer times if you plan to send the image via e-mail or upload it to the Internet. Higher resolutions are preferred if you are going to print or enlarge the photo. Depending on the quality of your printer, however, there is a point where higher image resolutions will not return better output quality. Scanning or photographing at a resolution higher than necessary will simply waste storage space, and increase loading an transferring times. If you plan to print to a high resolution device, however, high resolution images are preferable. Printing to 2400 dpi film for a glossy magazine or poster are examples of high resolution applications.

Q: What is meant by the term ‘color depth?’

A: A digital photograph is said to be True Color if it has a color depth of 24-bits per pixel (24-bpp), meaning the image may have up to 16.7 million colors. High Color photos are 16-bpp, or 65,000 colors. Photos at 8-bpp have 256 colors, which is adequate for display on computer screens or Internet use. 4-bpp photos produce 16 colors, which is the common color depth for windows icons.

Lower color depth values produce smaller file sizes, saving disk space and resulting in higher file transfer rates. 24-bpp may be desirable for printing. Grayscale images need not be greater than 8-bpp (256 shades of gray), even for printing.

From the examples given below, you will see that a 24bpp image takes up much more storage space than an 8bpp one. It is easy to calculate the file size of a photo, using the formula:

  Vertical pixels x Horizontal pixels x Color depth

Example

A 640 x 480 image at 8bpp (256 colors) produces a file size of:

  640 x 480 x 8 = 2,457,600 bytes, or 2.4MB.

The same image saved as True Color (24-bpp, or 16.7 million colors) produces a file size of:

  640 x 480 x 24 = 7,372,800 bytes, or 7.4MB.

It should be noted that the above file sizes were arrived at without compression. Saving a file as a TIFF with LZW compression can reduce file sizes considerably. The JPEG file format offers even greater compression rates.

Q: When saving, MGI PhotoSuite II allows me to reduce the number of colors in my image. Why would I want to reduce colors?

A: Reducing the number of colors from say, 16.7 million (True Color) to 256 colors will greatly reduce the storage requirements of the image. This is of great benefit if you plan to e-mail the photo to a friend or upload it to the Internet, since the smaller file will reduce transfer time over phone lines. The downside is that it can reduce the quality of the image, especially if it is to be printed on a color printer.

Q: I have a special photo I wish to upload to the Internet that looks great at True Color, so I don’t want to reduce the number of colors. What should I do?

A: Save the photo as a JPEG (.JPG), a format that utilizes compression to reduce file size while retaining 16.7 million colors. JPEG is a ‘lossy’ compressor, which means that some image degradation can occur at high compression levels. You can specify the amount of compression and decide what level works best for you. The default value offers good compression values while retaining high quality, enough so that most images are more than acceptable when viewed on a monitor.