Photography Beginner

Image quality & Picture size

The ‘Less is More’ principle is at work here for both image quality and picture size, but many people mistakenly go for quantity over quality, when quality should always win!  People often mistake picture size and image quality for the same thing.  Although they are linked, they are very different, but because of this, people can overlook one or both when setting up their camera.  They try and cram as many pictures on the memory card as they can.  So why is this wrong?  Because Picture Size and Image Quality have a direct effect of photographs when they’re printed out!

Picture size is the dimensions of your final picture in pixels (the little building blocks that make up the image). For example, a picture with the dimensions of 1800×1200 would be 1800 pixels wide and 1200 pixels high, giving a total of 2160000 pixels making up the final image.

Your camera offers you the option to increase or decrease the number of blocks (pixels) that make up the image, which in turn affects how many pictures you can get on your memory card.

WHAT PICTURE SIZE?

Imagine your photograph as a jigsaw made up of lots of small squares.  You have a choice to make this image up from 100 squares or to make the same image up with 25 squares.

When you look at both images, you can still initially identify what the picture is.  But which one would contain the most detail?

The answer would be (a) – the 10 pixel by 10 pixel image.

If you made the pictures bigger, which one would start to show the edges of the pixel building blocks first?  Obviously it would be (b) – the one made up of the fewest pixels – the 5 x 5 pixel image.  (This is called ‘pixilation’ and you see this effect when you try to enlarge a photo too much for the picture size.)

So whilst reducing the number of pixels in your picture size allows you to get more pictures on the memory card, the images contain less detail and definition which produces inferior quality photographs.

Image Quality dictates how the camera processes and stores the final JPEG image.  When you press the shutter, the internal processor in the camera has to convert the light that has brought the image of your subject into the camera down into bits of digital information that it can then store on (write to) the memory card.

It’s like the mechanics of turning speech into written text.  Your brain acts like the processor in the camera to allow you to convert what you hear into written words on a page.  Your brain can then decipher the written words at a later time and allow you to convert them back into a verbal sound that (hopefully) makes sense to someone else.

In a similar way, your camera’s processor converts the image of what your camera sees into a different format (digital information) which it then stores as an individual ‘file’ of information on the memory card.  This can then be read and converted back into a digital image either by a computer or printer.

So why do you have several settings?  This is because in order to save space, the processor has to compress (or squash) the image down.

It does this by looking at the image overall and then removing bits (pixels) of information in order to get it down to a certain size.  The pixels that are removed from the image are then discarded – deleted out of the image.

These deleted pixels cannot be restored.  The smaller the size you tell the camera you want, the more information it removes from your picture before storing it.

It’s a bit like telling it you want to store it in a small, medium or large box.  The bigger the box you ask for, the more of the original information you keep and so the better the quality you keep in your photographs.

You may find your camera has two or three different setting – Fine, Medium, Small/Normal.  These give a misguided impression that the lowest image quality will still produce a good acceptable image, but this is not necessarily the case.  (Further examination of image quality and print resolutions is discussed in a further part of this series).

Going back to the analogy of converting spoken words into written words, imagine trying to convert the written speech (1) below back to verbal sounds.

Using the camera’s compression criteria for producing Fine/Best setting for image quality, (1) thn ther wil b som los of detail, bt u cn mak out wht is beng rcrded.

However, if you decide to use a lower image quality setting, (2), more of the original letters of the verbal speech will be removed.  (2) Tn i wl tk ot mr f te ptgh t rdce i dn (actual translation – Then it will take out more of the photograph to reduce it down).

To convert the digital file back into a photograph, the computer has to make an educated guess at what color pixel originally filled the gap taken out by the camera processor, a bit like trying to put the missing letters back into the sentence.  The larger the area the computer has to fill in the harder it will be to accurately put back all the detail that was taken out.
How much more difficult was it for you to make sense of the second sentence because there were fewer points of reference to associate the words with?  Image quality is the same – the smaller the image quality you ask for, the less of the original remains, and the bigger the gaps for the computer to rebuild so as to convert the file back into a visual image.

If the image quality is too small, then your image becomes unusable as a printed picture.  So never compromise quality for quantity.  It is far easier to take the quality out than to put detail and quality back in once it has been deleted.  Always try to use your camera on the best settings.  If needs be, get a larger memory card, or carry a spare!

JPEG – You will see the file extension letters .JPG attached to each picture’s file name when you download your pictures from your camera onto a computer.
When you open the folder that your pictures are in, more often than not there will be a small version of each picture (called a thumbnail) and beneath that will be the name your camera has given to each picture followed by the .JPG format file extension the camera processor has converted the image to, e.g. MG8002.jpg.

The JPEG format of pictures, standing for JOINT PHOTOGRAPHIC EXPERTS GROUP (who are the people who created this system of image storage), is a way of compressing images that trades off some of the image’s quality for a reduction in the overall size of the image’s final stored size – the image has a varying amount of the total number of pixels removed on closure to give a compressed image size.

Whew! That was a lot of data…but I hope that helps!

So next we will be looking at what that “White Balance” is all about.

Sheila