July/August 2004 HelpLine

Mega-What?

    * The Honeymoon Is Over
    * Batchin’ It
    * Megapixels And DPI

The Honeymoon Is Over

Q)  My husband and I quit our jobs after our wedding to live in Oaxaca, Mexico, as an extended honeymoon. We had two months of wonderful photos on our digital camera memory card when our camera took a two-foot drop to the ground. It turns out that the SD memory card now has a short in it and we seem to have lost everything! Is there a way to recover a memory card that seems to have a short in it?

Katie and Rory
Via e-mail

A)  If it was just an accidental deletion or some other error, you might have success with file recovery software; however, I wouldn’t chance it with a hardware failure. With a confirmed short in your memory card, my guess is that any chance of recovering your images will come from a professional file recovery service. There are usually advertisements for a couple of companies in PCPhoto. Here are a few to try: MediaRECOVER (www.mediarecover.com), LC Technology RescuePRO (www.lc-tech.com), FlashcardFIX (www.flashcardfix.com) and Total Recall (www.recallusa.com). Don’t forget to let the recovery service know that your card was damaged and that you’re not trying to recover a deleted file.

For those of you going on extended trips, this scenario brings up some important points to consider. First, don’t keep all your photos on the card in the camera. Download and protect your images regularly. Many photo labs will now do this for you and put them onto a CD. You also can use several memory cards for added protection.

 


I hope that Katie and Rory will have success both with their file recovery and their life together. While the first anniversary gift is paper, I hear the second anniversary gift might be changed from cotton to memory cards!

Batchin’ It

Q)  Are there any programs that allow selecting multiple JPEG files and sizing all of them at the same time? For example, I want to take photos to display on eBay and size them to 400×400 all at once rather than one at a time.

J. Clark
Via e-mail

A)  Most of the popular image-processing programs and image-browsing software can do what you want. Look under the file menu of your program and you should find an item that can be used for adjusting a series of images. In Adobe Photoshop Elements (www.adobe.com), it’s located under Batch Processing. In Adobe Photoshop CS, it’s found under the Automate menu item. In Jasc Paint Shop Pro (www.jasc.com), it’s under Batch > Process. In Ulead PhotoImpact (www.ulead.com), it’s called Batch Convert. In ACD Systems ACDSee (www.acdsystems.com), you select the photos you want to change, go to Tools, then Resize.

The options for batch processing images vary with the software you use. Some programs offer simple resizing, which would work to display pictures on the Internet. They also may change file types, in case you need to convert a disc full of TIFFs to JPEGs, for example, so that the media card reader can display your images on the TV.

The software might also be able to batch rename a series of files from, for example, DSC0001, DSC0002, DSC0003 to MilfordSound001, MilfordSound002, MilfordSound003.

Some applications take batch processing into a more advanced realm. They allow you to run a series of image-editing steps on each file. You could add things like a copyright or watermark to your images. You also could run a sharpening filter on each image or make them all black-and-white.

 

 


Or, once you’ve discovered the series of steps required to make corrections to an image, you could assemble all those steps into a script or action that could be run on each file during batch processing.

Most of the manufacturers listed above have trial versions you can download. Try them out to see if they will do what you’re looking for.

Megapixels And DPI

Q)  Digital cameras use megapixels as their measure of resolution, but I can’t find an explanation of how to equate megapixels to dpi. In other words, at 300 dpi, how big can you make an image from a 5-megapixel camera? It’s said that a 5-megapixel camera takes sharp 11×17 pictures, but at what dpi?

Bob Daniels
Toledo, Ohio

A)  There really isn’t a standard for referencing megapixels to dots per inch (dpi), or pixels per inch (ppi), for that matter. You can’t judge the area of a town by counting how many houses it has. You need to know how far apart each house is from another. It’s the same with pixels. Your camera’s image sensor is jam-packed with photosites (the technology that receives the incoming light from your lens). These photosites are used to create the pixels that are stored on your memory card. They will give you a total number of pixels (5 megapixels, for example), but pixels or dots per inch can’t be determined from a pixel count. You must know dimensions.

When you download the image into your computer, you’re bringing in pixels, but you haven’t decided how far apart each pixel is going to be from the next. That will depend on how you want to use the image. If you were to take those 5 million pixels and display them on a monitor at the usual 72 dpi to 96 dpi, you’ll end up with such a large image that you’ll display only a small portion of it.

Regarding your question about what will happen when you print the image, you can adjust either the image dimensions or the dpi for the original set of pixels that came from the camera. These two values are tied together like a seesaw. As the dpi goes up, the image dimensions go down, and as the image dimensions go up, the dpi goes down.

 

 

So, let’s see what happens if you start with a 5-megapixel file. As an example, I’ll use a 2500×2100-pixel image. When I bring it into my software, it might be at a resolution of 72 dpi (or ppi, as image-editing programs like to call it). If I kept that dpi specification and tried to print my image, it would be sized at about 34×29 inches. You wouldn’t be happy with the quality, as 72 dpi isn’t a printing resolution.

Now, if I take that same image (making sure that Resampling is turned off in the Image Size dialog box) and change the dpi to your request of 300 dpi, the software will update the numbers in the Image Size and Resize boxes to about 8×7 inches. While that answers your question specifically, I don’t want to stop there.

If you’re asking about 300 dpi b
ecause you’ve heard that’s the standard output for printing, you might want to consider some other numbers. Try experimenting with values from 160 dpi to 260 dpi to see what printers can do with your image. The technology inkjet printers use today offers superb results at 200 dpi that easily match the old 300 dpi needed by printers from a few years ago.

Getting back to my example, a 180 dpi resize of the 72 dpi image will produce dimensions of about 14×12 inches, which is easily resized to the 11×17 inches you mention by interpolating, or resampling, the original file. Digital camera image files resize extremely well. I’ve seen 11×17-inch prints from 4-megapixel cameras that rival a traditional film print. When you interpolate, however, you do need to do some slight sharpening.

If you become familiar with how resizing works with your image-editing program, you won’t have to write me a letter when you’re investigating an 8-megapixel camera (not that I don’t like letters!). Just open up your software and create a new document that contains 8 megapixels, then start adjusting the dpi to see what kind of image dimensions you end up with.
 

If you have any questions, please send them to HelpLine, PCPhoto Magazine, 12121 Wilshire Blvd., Ste. 1200, Los Angeles, CA 90025 or helpline@pcphotomag.com.

 

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