By Mark Mayhew
Format
The majority of this section is
about preparing your pictures for the web, rather than for printing. The reason
I make this statement is because the dpi does not need to be so high for the
screen. I will not go over it all again as everything you need to know about
resolution is in my earlier articles.
So lets begin by saying again that every time you save a picture in jpeg format it's quality will decrease like copying video tape. Take all your copies from a master and of course they will all have about the same dergradation. Take a copy from a copy and you have gone down another rung of the ladder. And so it is with jpeg. So first an foremost pictures should be scanned at around 300dpi for the best monitor quality. Assuming you have scanned 7 x5 print the picture will be too large to viewed on a standard monitor at 800x600 resolution, so you can then use the software to reduce it in size. Say around 450 pixels w x 700 pixels h.
Now you have your print on screen and about the right size you want to save it. Saving in jpeg format in that size allows you lots of options. At the best quality save, the finished picture will be around 260k in compressed format on your hard drive. Moving up the scale slightly you can save the picture and it will be only around 70k in size and you don't lose too much in the quality. If you go the whole hog and go for full compression then the file size is small, around 17k, but the image quality will drop right down.
I hope Adobe will forgive me here, but here is how they put it.
When saving in JPEG format, you can specify an image quality and compression level for the file. To specify image quality, enter a value between 0 and 10 or choose an option for Quality; to specify the amount of compression, drag the slider. A trade-off exists between the image quality and the amount of compression; an image compressed using Maximum quality is less compressed (and thus takes up more disk space) than an image compressed using the Low quality option
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Here we have the original picture. Click on it to see the full size image. It takes up 67k on the hard disk and opens out to 1017k in Ram | |
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| Detail from 231k high quality, low compression. | Detail from 67k mid quality, mid compression. | Detail from 17k low quality, high compression. |
So what's going on? The jpeg format is basically a compression program that simply put, squashes up all that digital information and makes the file size smaller! (Yea I don't really understand it either, but you don't need to!) The higher the compression the lower the quality. Sorry I think I already said that. Ok seriously the point is that if you are putting your pictures up to a server and you only have about 5meg of space using 300k files will soon fill her up!
Play around and find a compression level you are happy with. So you have the quality in your pictures that you want and can get the pictures all on your server. Remember also that the the larger the file the longer it takes to download.
Contrast
Most of the software you use these days
can automatically correct the contrast, brightness and colour correction for
you. The two pictures below give a good example of this. Working in a studio
with only two lights the photographer had the problem of very little modelling
(light) in the subject and the scan darkened things a little as well. So simply
by using auto correct the right hand image was produced.
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| The beauty of digital pictures and software is the fact it is like having your very own darkroom, but without all the hassles. | |
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| It's wonderful as you can play around with your images to your hearts content. | |
Play around, have fun and it's certainly worth a visit to any of the numerous sites that provide tutorials on using the major paint packages.
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Then when you are really practiced you don't even have to worry about lighting and all the rest of it when you take the picture. You can smooth and paint the models face, put in the lighting as it should have been, add all the catchlights you like and turn out pictures like this one of Kylie Minogue on the left. Did a little sarcasm creep in there? I know I prefer a natural well lit studio shot, but that's me! |
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