Digital Camera Systems Ltd
Killeshin Heights
Co Carlow

Beginner's Photo Course

A lot or even more? - Resolution

Hardly any other aspect of digital photography causes as much debate as the importance of "resolution". While this is justifiable to some extent, it's also comparable to the desire of car drivers for more and more horsepower, despite chronically congested roads ...

To understand this term, you first have to call to mind the structure of a digital photo. It is made up what are known as picture elements or "pixels", which are the smallest building blocks of this kind of image.

A vast number of these pixels are pieced together like a mosaic to produce the digital photo - rather like a piece of graph paper on which you can fill in individual boxes with a pencil and then recognize a picture-like pattern when you look at it from a distance.

CCD sensor and pixels

The resolution of a "graph-paper picture" like this is equal to the number of boxes on the paper.

The situation is similar with digital cameras: with the help of an enormous number of minute, light-sensitive photodiodes, known as CCD elements, they:

1. break down the image captured by the lens into millions of individual "colour boxes" - i.e. they "resolve" it into pixels
2. save them
3. display them on their LCD monitors
4. or transfer them to a computer.

The more of these photodiodes there are on the sensor of a digital camera, the higher its resolution becomes. In the technical data, this resolution is either described by way of an exact number of pixels (e.g. 2,048 x 1,536 pixels), or the value is simplified by stating the number in millions of pixels. In computer jargon, the word "mega" is used to indicate a million.

Having worked our way through so much technical language, we know now that a 3-megapixel camera is a model whose recording sensor contains:

Roughly

3 million individual photodiodes or pixels

Usually

2,048 pixels horizontally and 1,536 pixels vertically.

If you multiply these values, you get the magic number (exactly 3,145,728).

In practice, this simply means that the camera can break down any motif you point its lens at, be it the Eiffel Tower or a ladybug, into 3.1 million mosaic tiles.

If you photograph a motif of this kind with a 3-megapixel camera, this resolution has enough reserves to make even small details visible.

• The more pixels a camera has at its disposal, the greater its ability to reproduce even the finest details and structures.
  • Like a mosaic with a large number of small tiles as opposed to a much coarser mosaic with only a few, large tiles.
  • You don't have to have maximum resolution all the time.
• The resolution (= number of pixels in a digital photo) says less about the quality of the image than about the size in which it can be printed on paper.
• The higher the resolution, the larger the image file - and the smaller the number of image files that will fit on a memory card.
• Even if you have a high-resolution digital camera, you don't always have to take your photos at 'full capacity'. Almost every camera lets you vary the resolution setting from one shot to the next and thus take photographs with a lower resolution even with a 5-megapixel camera.
• 2 megapixels is usually perfectly adequate for presentation on a web site, e-mailing or producing a paper print up to the standard format of 10 x 15 cm.
• The resolution can certainly be a little higher for larger print formats or selective enlargements: 3, 4 or 5 megapixels will stand you in good stead in this case, depending on your individual requirements.

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Last updated on Wednesday 9 July, 2003 10:14