Image Resolution

There are different ways of talking about resolution, depending on whether it is the camera, or the monitor or printer being considered.

Camera Resolution

Available Lumix
10 megapixels
7 megapixels
5 megapixels
3 megapixels
2 megapixels
0.3 megapixels

The resolution of your camera is usually measured in megapixels. This is a count of how many pixels (picture elements) the image will contain. So an 10 megapixel camera will produce an image with 10 million pixels. Usually, a camera will have a setting which allows you to change the number of pixels actually recorded in an image. Also, although a camera sensor might have 10 million pixels, the aspect ratio that you chose to shoot at will effect the actual number of pixels recorded in the image.

So, for example, the Panasonic Lumix DMC-FZ28 has a stated sensor size of 10 megapixels, but in the Picture Size menu there are 6 different settings available, as shown in the table on the right. This means that you can control the resolution of the image that the camera captures.

The higher the resolution, the more information the camera captures and the more information in an image the better the quality of the resulting image will usually be. However, the larger the number of pixels in an image, the larger the file will be and, therefore, the more room it will take to store on the memory card (however, note that the image compression setting will also effect the file size).

In addition to different resolutions, this camera can also shoot images in 3 different aspect ratios, resulting in 3 different maximum image sizes:

Ratio Dimensions Pixel Count Comment
4:3 3648x2736 9,980,928 This is the standard for digital cameras
3:2 3648x2432 8,871,936 35mm film cameras shoot in this ratio
16:9 3648x2056 7,500,288 HDTV has this ratio

This table shows how big the image would be with the picture resolution set to maximum, but with different aspect ratios selected. If a smaller resolution had been selected, then the three aspect ratios would produce proportionately smaller images.

Aspect Ratio ExampleYou can see the visual result of these different aspect ratios in the image to the left.

The overall image was taken at a 4:3 ratio, which makes the maximum use of the sensor in this particular camera.

The outer cyan rectangle shows where a 3:2 ratio image would fit. This loses a little at the top and bottom of the picture.

The inner red rectangle shows where a 16:9 wide screen image would fit. Clearly this loses much more from the top and bottom of the image.

As a general rule, you should set the aspect ratio of the image to the setting that most closely matches the camera's sensor. For more consumer and bridge cameras this will be 4:3. For digitial SLR cameras it will more likely be 3:2. There are currently very few stills cameras with a sensor aspect ratio of 16:9.

So, generally speaking, you should set the resolution of the image at maximum and chose an aspect ratio that matches the camera sensor. An image with a higher resolution has the potential to be a better quality image simply because you have more information in the image to work with in the post-processing stage.

However, as we see below, depending on how you intend to use the picture, the extra information in a higher resolution image will be wasted.

Screen Resolution

Often people simply look at their images on a screen, either a computer or a TV. Resolution on a screen can be stated either as the total number of pixels displayed, or as a pixel density. You need to be comfortable with both ways of thinking.

So, for example, as of 2013, a wide screen computer monitor might have a total screen size of 1600x900 pixels, equivalent to a 1.4 megapixel image. This means that on a good 22" monitor the pixel density on is now 90ppi (pixels per inch) or higher. So, if I wanted to display a full resolution image from my Lumix on my computer monitor it would appear over twice the size of the screen! Therefore, for example, when you are preparing images to be used in a web page, you need to drastically reduce their size before hand. The image used above is only 400x300 pixels, which is a decent size for an illustrative example in a page like this.

For comparison, a 1080p High Definition TV has a resolution of 1920x1080 pixels, roughly equivalent to a 2.1 megapixel image. The pixel density of a 42" wide screen TV then works out at around 52ppi.

Print Resolution

When we think about print resolution, the total number of pixels is less important, and the pixel density is the usually quoted figure. Note that for print, it is usually described as dots per inch (dpi) but this is a little confusing because it actually takes 3 or 4 drops of ink to make one image pixel. This is because the printer mixes three or four different coloured inks in different proportions to make a single coloured pixel. So, although some printers claim print densities of 4800dpi, this does not represent the real pixel density of the actual printed image.

Most good inkjet printers can print a good image at 600dpi. How big would my full resolution Lumix print be if I printed it? The image from the camera is 3648x2736 pixels, so at 600dpi this would be 3648/600 x 2736/600 or roughly 6"x4.5".

Thus we see the main different between an image presented on the web and an image presented in print. A full resolution image from a 10 megapixel camera is much too big to put in a web page, but will only produce a 6"x4.5" print at a good quality.


You can find additional information about resolution at the following pages:

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