Jpeg Camera Settings
Jim Doty, Jr.
Almost every digital camera allows you to save files in a jpeg format. Some also allow you to save in a "raw" format. If you don't know what that means, read my Raw vs Jpeg article elsewhere at this site.
camera is saving files in a jpeg format, it means the internal camera chips are processing your image between the time the raw image is captured on the imaging sensor and its conversion to jpeg. To get the most out of
your images, you need to have some understanding of what the camera is doing.
The best way to do that is to read the camera manual carefully and learn what the settings do. This brief article can serve as
an introduction before you go read in your camera manual.
The imaging sensor in your camera captures the same amount of information every time. If you set your camera for a lower resolution, the camera throws away a certain amount of information (pixels) to give you a lower
resolution image with smaller file size. This may or may not be bad depending on the quality of the programming in your camera.
Using your camera's highest resolution means saving the maximum amount of
image information, and also makes possible larger, high quality prints. The primary disadvantage is that these files are larger. If you only want an image to e-mail or put on the web, a smaller resolution file is fine
and saves space on your storage card. If you want nice looking prints, a higher resolution is in order.
Resolution and Print Size
As a general guideline, you need about 300 pixels of digital image size to get one inch
of photographic quality print size. That means if your digital image size is 600x900 pixels, you can get an excellent quality photographic print (all other things being equal) of 2x3 inches. 1200x1800 pixels of image will give you a quality 4x6 print.
Working in reverse, take your desired print size in inches and multiply by 300 to get the digital image size you will need. To get a quality 8x10 inch print, you will need a digital image that is 2400x3000
pixels. For a 12x18 inch print, you will need a digital image file that is 3600x5400 pixels.
As a side note, how well an image looks on your computer
monitor at 72 pixels per inch has nothing to do with how well it well look as a print. A 400x600 pixel image may look great on your monitor at an apparent size of about 5x8, but it won't make a great looking 5x8 print.
You can always use your digital imaging software to "ress up" or interpolate up (re-size) your image file to a larger size. The
software basically "makes up" pixels to make the image bigger. To do this, you need a decent sized file to begin with, and the quality of pixels makes a difference too. A 3 MB file from a Canon D30 can be resized
to file that produces better prints than many point and shoot cameras with a 4 or 5 MB file size due to the nature of the way the D30 CMOS sensor. Not all pixels are created equal.
Jpeg images are compressed, or reduce in size. Jpeg is a "lossy" compression. This means you lose
some quality when the image is saved. Jpeg uses certain formulas to throw away or add back pixels. If there are five light blue pixels in a row, jpeg will throw some of the middle ones away when the image is
saved. When the file is opened again, jpeg will assume the missing pixels in the middle are light blue and put them back again. Since it does not actually keep track of what pixels were discarded, it must guess each
time at what to put back. This is a bit oversimplified, but it should give you an idea of what is going on.
This process actually works quite well so long as you remember that the greater the
compression (the more pixels that are thrown away) the greater the quality loss and the smaller the end file size.
If you are choosing between "Jpeg-Fine" and "Jpeg-Medium" on your camera (the terminology
will vary from camera to camera), Jpeg-Fine will have less compression and give you a bigger file size than Jpeg-Medium. Jpeg-Fine will also give you better quality image.
Which you choose will depend on the final purpose of your image. A photo to be e-mail could very well be saved at a higher compression rating. A large print to be sold would most
likely be saved with the least compression (and most quality and largest file size).
So how do you decide? You will need to experiment. One good way is to take the same picture at different settings,
and check them out. Make prints in different sizes to see where the quality difference begins to show. When in doubt, go with less compression (and buy bigger memory cards).
To get an idea how sharpening works, open a digital photo file in your favorite imaging processing
software and play with "unsharp mask." This is an oddly named filter which actually enhances the apparent sharpness of an image by creating halos around edges in the image. Rather then worry about how it works, just
play with unsharp mask and see how it changes the apparent sharpness of your image. Too little and your image can appear soft. Too much and your image can appear unnatural.
Almost all digital image files,
whether they originated with a digital camera, or came from scanned film, will be improved by a judicious use of unsharp mask.
Any jpeg file
from a digital camera has had some sharpening already applied to it. Good cameras will give you some control over how much. If you don't want to mess too much with your digital camera files, set the amount of sharpening
to something approximating normal or average. You may need to experiment. What you see on your computer screen well help, but a nice sized print well tell the final story.
If you are willing to work with your files it bit, it is best to minimize the in-camera sharpening. Do most of the sharpening after the fact in your digital imaging software.
This gives you more control, since the amount of sharpening that an image needs is in part determined by the final print size. The same file printed at 5x7 inches will need a different amount of sharpening than if it is
printed out at 11x14 inches.
The default amount of sharpening in a professional or serious amateur camera is usually less than in most point and shoot cameras since serious photographers would rather make
the sharpening decisions themselves.
Some point and shoot digital cameras are known for oversharpening digital files. How do you know which ones? Go
to my LINKS
page and check out the digital review sites, especially Digital Photgraphy Review.
I save all of my primary files with as little sharpening as possible.
Only when I resize the image to print it out (or put it on this web site) do I go to unsharp mask.
Saturation has to do with the amount or intensity of color. The higher the saturation, the more intense the color appears. (FYI: You can get more saturation in a digital image on your computer screen then you can get on a photographic print. Some software will warn you if some parts of your image are
"out of gamut" or beyond a printable intensity range.)
Here is an image at a normal saturation level.
This is actually a scan of a slide with the saturation set in Photoshop to match the color intensity of the
original slide. You can see a larger version of this image on the Taiga page and you can better idea what it was like to be there.
Here is the same image at a very low saturation level.
The image looks pretty blah since much of the color is gone.
This is the same image at a high saturation level that is far beyond the color intensity of the original scene.
These colors look unreal, at least on my monitor.
For folks that don't want to mess around too much with their digital images after the fact, the saturation or color intensity levels should be set close to normal. Some folks who like to manipulate their images after
the fact tend to set the saturation levels a little lower than normal and increase them to the level they want in their image processing software. As they say, season to taste.
Some less expensive digital cameras tend to set the saturation levels on the high side to give folks a more vivid looking image.
Resolution, Compression, Sharpening, and Saturation are just a few of the settings you may find on your camera, but this are some of the most important and should get you started.
Make a promise to yourself that you will read your camera manual and experiment with your own camera settings. Be sure and read Fixing Digital Camera Files.