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Computer Users’ Group

November 17, 2004

SP2 and Image Processing

Windows XP Service Pack 2

SP2 is a major security update for Windows XP. It patches many of the security holes and is a must for anyone who wants safe computing especially if you’ve missed some updates along the way. Here’s where you go to get a copy of the SP2 update CD. It’s free and anyone with a dial-up connection should order one. Backup your data before you start. Installation is straight forward but it takes time. Most problems with the update seem to occur when people have very unique software installed although some problems have occurred with network setups.

Preserving Old Family Photographs

The emphasis here will be on preserving a batch of old photographs by scanning them into your computer and burning them to a CD or DVD and making corrections if necessary. But we’ll also try to cover scanning and correcting an individual photo as well.

Plan. How will you use the images? Are they all one size? Are they all black and white or all color or mixed? Where will you save them? Will you just copy them or correct them?

Usage. If you are only going to email them or put them on the web, scan at 75 dpi. If you want to enlarge them, print them or just save them, consider the resolution at which they should be scanned.

Size. Time can be saved if you scan all photos of the same size sequentially, separating black and white from color and grouping them.

Location. Create a meaningful folder (or folders) to receive these images. Perhaps a sub-folder (or folders) under My Pictures. I have a folder named “Historic Images” and sub-folders under that are by family name.

Scanning. Most scanners come with two types of software; scanning software appropriate to your scanner and image processing software, usually an Adobe product. You use the scanner software to scan an image and save it to memory. You use the image processing program to “acquire” an image from the scanning software and open it for correction. Once an image has been scanned by either program, you can open it and work on it in your image processing program. You may then apply necessary corrections or just save the image as is.

In either event, you will have a choice of “Preview” or “Scan”. When archiving a large number of photos, the approach should be to separate photos by size and segregate any that are so under- or over-exposed that may need special scanning. Then “Preview” the first photo of the group and made sure that the size, resolution, brightness and contrast and image type are properly set. Many old “Black and White” photos will show up as “Color” photos due to discoloration. Set the scan to “Black and White Photo” or “Grayscale Image” depending on your scanner. Complete the scan of that image and then place each subsequent image of the same size and type in exactly the same spot. Press “Scan” to by-pass “Preview”. Proceed in the same manner to the next size and type of image. (For scanning only a few individual images it may be better to take the time to preview and correct each at the time of scan).

Now review what you have done by looking at all of your scanned photos and re-scan any that need major correction. Getting the scan right makes subsequent editing easier.

The Histogram. The histogram shows the tonal range that you captured. If either end is truncated, there is data lost that you can never recover. Re-scan any images that fall in that category shifting the brightness to insure that nothing is lost.

Resolution. The resolution that you use to scan is determined by several factors. You have to start at the ultimate size and purpose to determine the appropriate scanning resolution. Here are two guidelines to consider:

At the size you want to email an image or put it on the web, it should have a resolution near 75 dpi (dots per inch).

At the size you want to print it, it should have a resolution of between 150 and 300 dpi. Most any image that you scan will have to be cropped in order to become an eight by ten image.

Consider the following math: As you double the width, you double the height and halve the resolution. Thus the old standard 3 x 5 image could have it’s dimensions doubled to become a 6 x 10. That would require scanning at 300 dpi in order to end up with an image with a resolution of 150 dpi. But if you want the full 8 x 10 then you have to enlarge the image by 2.66 times to get an 8 by13.3 image. Thus, nearly 3.3 inches have to be “cropped” off. Can your image stand to be so massacred? Consider those areas that add nothing to the picture. If you can’t sacrifice something, then consider leaving some blank space on both sides. But remember, if you do plan to enlarge by 2.66 times you have to scan at between 400 and 800 dpi in order to get a printing resolution of between 150 and 300 dpi. See the following table.

Original Size Inches Enlarged size Inches Scan Resolution dpi Lost to Cropping In.
2.5 x 4.5 8 x 14.4 480 to 960 4.4
3 x 5 8 x 13.3 400 to 800 3.33
4 x 6 8 x 12 300 to 600 2.0

Scanners: Most scanner programs cloak the true resolution behind a screen that asks your ultimate purpose and then determines what it thinks is best. Some allow for “custom” settings where you can be in charge. Understand these settings by reading your manual or your help file so that you can get the best output for your purpose.

Format: There are many formats available in which to save your images. Which ones to use depend on the ultimate purpose of scanning them. One is always guided by an inclination to conserve disk space. But will your great-grandchildren say, “I wish they’d scanned that so I could see more of the detail”. I recommend saving everything in TIFF (truncated to TIF for DOS) format at the highest reasonable resolution. For small images, that would be 600 to 1000 dpi and for larger images, 300 dpi. If you’re planning on editing any images then it’s important to save them as TIFF images and keep them in that format until all of the editing is done. Then see tradeoffs below.

Tradeoffs: Not every image that you want to save is worth preserving for its content or it may mark an historic event but is not of very high quality. You can treat your clear, crisp images one way and the fuzzy or less important images another way. Consider saving them as JPG images to save disk space. JPEG (truncated to JPG for DOS) is a graphics format that compresses files to save space. JPEG is a lossy compression format in that some data is destroyed and is estimated on re-construction. Repeatedly opening and saving a JPEG file results in further deterioration. Save as JPEG only after all editing is done. The more you compress the file (smaller file size) the more loss occurs. If you have the space, leave as TIFF

Correcting the Images. Here are some examples:



From this

To thishoward'sfarm-21.jpg

Images need to be corrected using a Graphics (image processing) Program. We’ll use three to show what can be done. Two of the three are free but they don’t do everything that we want but they do do enough to get by. The first step is to open a file in a program that will let us examine a histogram. Adobe Photoshop Elements will do that for us and will do everything else that we want to do. The histogram lets us see if we left out some highlights or lowlights. If it’s not truncated at either end we can proceed. If it is truncated, it should be re-scanned and the brightness adjusted to move the histogram left or right as needed. Most images have some black and some white in them so that the histogram ought to extend from one edge to the other. In Photoshop Elements there are three commands to that you can use to adjust the brightness and contrast. One is ENHANCE/AUTO LEVELS and the other is EQUALIZE under IMAGE/ADJUSTMENTS. If those doesn’t satisfy you go to EDIT/UNDO and then ENHANCE/ADJUST BRIGHTNESS/CONTRAST/LEVELS. There you see a histogram of the image. You can click on the eyedropper on the right and then point to the whitest part of the image and click. Repeat for the left eyedropper only point to the darkest part of the image. If you are not satisfied, UNDO and try moving the right triangle until it falls under the right edge of the histogram and click when you get the highlights that you want. Repeat for the lowlights with the left triangle.

In IrfanView you can manually adjust brightness under IMAGE/ENHANCE COLORS but nothing is automatic and it doesn’t “stretch” the histogram. However adjusting the brightness and CONTRAST may give a pleasing result. Paint does not have this capability. If you have a lot of images and you want them done right, an investment in a good program may be worth while.

Here's what we worked on.

Photo was taken about 1935 and is colored with age. We converted it to greyscale, removed the cracks and tears and adjusted the levels.

If there are blemishes to correct, the CLONE STAMP in Photoshop Elements may be the way to correct them. It takes a good part of the image to replace the defective part. Look through the image to find a shade and texture that matches what is missing. Usually that’s very close to the damaged area. Large areas are much harder to fix; it may be necessary to use the same source spot several times and hope not to get a pattern. To use it, you click on the CLONE STAMP tool and select from the tool bar BRUSH TYPE, SIZE, MERGE TYPE, and OPACITY. Then move the cursor to the spot to be copied from and hold down ALT and CLICK. Move the cursor to the damaged area and hold down the left mouse button to paste the source area over the damaged area. If you don’t like what you just did, go to EDIT and click on UNDO. It only UNDOES what you did just before the last mouse click so do it one mouse click at a time. Review and accept what you’ve done or undo it and start over. However you can click on STEP BACKWARD to undo multiple corrections.

Perhaps the damaged area is large enough that a section of the image can be cut and pasted over it. While this may be unlikely, the technique is useful for editing images. Whether “doctoring” historic images to change history is appropriate depends on your conscience. But editing modern images to achieve an affect is certainly fair game. Things like swapping heads or adding or deleting individuals.

Start by planning what it is that you want to do. Know the resolution of the image you’re working with and if you’re transferring parts from one image to another, know the resolution of that also. Select the Magnetic Marquee tool and carefully position it at a point on the outline of the part of the image to be “copied” and “click”. Move to a new spot not so far away that the line doesn’t follow the outline of the image. “Click”. Repeat until you’ve returned to the original point. “Double click”. If you make an error along the way, press BACKSPACE to back up.

When you have created a “marquee” around that part of the image, enter CTRL-C to copy it or CTRL-X to cut it out. If you’re going to paste it back into the same image, press CTRL-V. Point to the image and “drag” it to where you want it. Use the corner “handles” to resize it; they move both dimensions; the side and top and bottom handles “stretch” or “shrink” the image in that direction only.

Before you paste from one image to another, look for all of the differences that there may be. Is the light from the same direction? Is it sunny in one and raining in the other? There are many things that can made an image look “fake”. Consider them before you proceed.

When you have what you want, it’s time to burn them to a CD or DVD. How you do it depends on the program that you use and how you organized the images and their folders. Many programs allow you to just drag them onto an icon and then proceed to burn them. Don’t try to do anything else during the burn process. Shut down other programs. If these are especially important images, consider creating several copies and putting one in a safe deposit box, sending one to your kids or grandchildren to keep in a safe place. The easiest time to make extras is when your software asks “Do you want to create another disk?”

Perhaps you should create one disk without any labeling or marking other that a brief title marked on the hub. Reports of disk deterioration due to labels or marking suggest one unmarked disk will help to guarantee that the images survive.