Frequently Asked Photo Questions for April

Have a question about digital photography? Send it to me. I reply to as many as I can--though given the quantity of e-mails that I get, I can't promise a personal reply to each one. I round up the most interesting questions about once a month here in Digital Focus. For more frequently asked questions, read my newsletters from January, February, and March.

What's the Best Photo File Format?

I recently had some prints made from photos I took with my digital SLR. I am not impressed with the quality--they are very grainy and some have a slight blur. Is this because of the picture format? I can shoot JPEG, RAW, and others. Which file type should I use, and for what occasion would I use others?
--Dennis Burdick, The Villages, Florida

Most digital SLRs and even many point and shoot cameras give you the option of JPEG or RAW, Dennis. Some cameras also throw in the TIF format. In general, most people will get the best results from their camera's highest quality JPG mode. The RAW format captures more color and exposure information than is visible in the JPG, which is ideal if you plan to edit the photo afterwards in a program like Adobe Photoshop. (Read "Using Your Camera's RAW Mode" for more on this.) But if you aren't the sort of person who tinkers with your photos, avoid the RAW format; it isn't white balanced or sharpened, so unedited RAW results are generally inferior to a well-shot JPEG.

In your specific case, grain and blur are not the sort of thing caused by--or solved by--any particular file format. Instead, those are issues that can be fixed by learning the photography basics, like how to use your ISO, shutter speed, and aperture. For tips on dealing with common photo problems like the ones you describe, read "5 Common Photo Problems, Avoided or Solved."

Choosing a Scanner Setting

I'm scanning old negatives with a film scanner. I can chose from many different settings, such as TIF or JPEG, and various levels of compression. The default setting gives me a TIF with a file size of 67MB. If I capture in JPEG format, excellent quality file size is still 67MB, and high quality gives me 11-14MB files, and good quality is about 5MB. When I edit photos with Picnik, the maximum file size the program can process is 16MB, so scanning with excellent settings doesn't seem to make sense. So should I use the Excellent setting, or the High setting? Am I losing any quality, and if so, how much? When I compare the same picture with both Good and Excellent settings, I don't see a difference on my monitor.
--Vincent Thompson, Ontario

The answer all depends upon how you plan to use your photos and how picky you are about image quality, Vincent. Consider music lovers for a moment. Many folks are perfectly happy listening to low-quality digital music on tinny ear buds. Me? I consider myself an audiophile; I am meticulous about ripping CDs at 320 kbps (the highest bitrate for the MP3 format). I won't listen to music sampled at 128 kbps or streaming radio. But it turns out that there are even more dedicated audio snobs who put me to shame. I know folks who listen to vinyl only because they think CDs and all digital music, regardless of the sample rate, sounds terrible.

So, back to the issue at hand. If you are scanning these slides as true "archival quality" or "reference quality" originals, then you would want to scan them at the very highest quality possible: TIF, which is a "lossless" format. But there's a cost to doing that because TIF is a cumbersome format to work with. Instead, the highest-quality JPEG is probably good enough if you are not a professional photographer. If you are even more casual about your photos and aren't worried about preserving every bit of color, tone, and resolution, then the Excellent--or even Good--quality setting on your scanner is probably fine for your taste. Of course, if you plan to edit your photos in an online tool like Picnik, you probably aren't concerned about preserving reference quality fidelity in your photos anyway, and lower-quality scans are adequate.

Photo Quality, Size, and Resolution Explained

I have seen pictures that completely fill my 22-inch monitor with excellent quality, and when you check the size they might only be 200KB or even less. How do megapixels relate to this?
--Shahid Husain, Jackson, Mississippi

This issue always seems to confuse folks, so thanks for asking, Shahid. There are a variety of values associated with photo size/resolution/quality, and they are only somewhat related to each other.

Let's start with megapixels. That's the key spec by which most cameras are sold, and it refers to the sheer number of pixels in the photos. A 1-megapixel camera takes photos with a million pixels in them; a 20-megapixel camera captures 20 million pixel photos. Think of it like a grid that tells you how wide and tall the photo is. For example, my 16-megapixel camera takes photos that measure 4928 by 3264 pixels. Multiple those numbers and you get 16 million pixels. Note that this says absolutely nothing about the actual quality of the photo--just the size.

Then there's the file size. A photo might be 16MB, 2MB, or even just 100KB in size. This measures how much space the photo takes up on your computer's hard drive. There's no direct relationship between file size and megapixels, because file size also depends upon the amount of compression used to save the photo. A TIFF or a RAW photo generally has no compression, so all 16-megapixel RAW photos are always exactly the same size. But if you look at a hundred 16-megapixel JPGs, you'll find that no two are the same size. The file size depends upon the compression used to save the photo and the amount of detail and color in the image to begin with. So the file size can give you some hints about the quality of the photo, but I wouldn't try to read too much into that, either.

You mentioned that even seemingly small photos look excellent on your computer monitor. That's not surprising. No matter how many millions of pixels are in a photo, it'll always be resized to just 1280 by 1024 on your monitor, or however many pixels your display is set to.

As you can see, measuring image size and quality is difficult. And I've overlooked the most important consideration: taking a great photo to begin with. The photo needs to be focused sharply and properly exposed. All the megapixels in the world can't fix a bad photo.

High Dynamic Range Revisited

Loved the article on creating high dynamic range photos using Ulead's PhotoImpact. Is there a way to achieve similar results using Adobe Photoshop Elements 8?
--Carol Krom, Miami, Florida

Photoshop Elements does not have a high dynamic range feature built in, Carol, but there are free programs you can try. For example, I have written about Luminance HDR, which works nicely. And if you want to stick with Photoshop Elements, you can "fake" HDR photography in that program using the technique I described in "Improve Your Exposure in Tricky Lighting."

Hot Pic of the Week

Get published, get famous! Each week, we select our favorite reader-submitted photo based on creativity, originality, and technique.

Here's how to enter: Send us your photograph in JPEG format, at a resolution no higher than 640 by 480 pixels. Entries at higher resolutions will be immediately disqualified. If necessary, use an image editing program to reduce the file size of your image before e-mailing it to us. Include the title of your photo along with a short description and how you photographed it. Don't forget to send your name, e-mail address, and postal address. Before entering, please read the full description of the contest rules and regulations.

This week's Hot Pic: "Warrior Dance," by Ron Lashley, Flora Vista, New Mexico

Ron writes: "I took this photo in Farmington at an Indian dance demonstration which included several tribes like Apache and Navajo. I used a Sony A300 with a shutter speed of 1/160 second; it was somewhat difficult due to the dancer's motion. I used Topaz Remask to remove the background, and then applied Topaz Clean and Simplify along with some hand painting to complete the effect."

This week's runner-up: "Hiding," by George Fritzsche, Bayport, New York

George writes: "I took this picture while playing with my son. We were playing hide and seek at a local beach on Long Island. I took my camera out and went around the other side of some playground equipment. I got this picture right before my son found me hiding."

George used a Canon EOS Digital Rebel XSi.

To see the March winners, visit our Hot Pics slide show. Visit the Hot Pics Flickr gallery to browse past winners.

Have a digital photo question? E-mail me your comments, questions, and suggestions about the newsletter itself. And be sure to sign up to have Digital Focus e-mailed to you each week.

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