Q&A - Digital
Some nice, straight-forward explanations of boring, complicated, computery stuff
that you probably need to know, but aren’t very interested in.
It’s a sort of cross between a fairy and an elf; actually, no, hang on a minute, that’s not right…
It’s the smallest single unit or block of colour used to make up part of a digital image.
It’s the way a computer stores data.
Conventionally, a file format is described as *.FormatName. So, a JPEG file would be described as a *.jpg file.
The most commonly used file formats for images are JPEG (.jpg) and TIFF (.tif).
Different file formats have different advantages and disadvantages. If you’re not sure, use *.JPG.
No, it’s a misconception. Saving an image as a JPG and then printing it, works perfectly well.
However, the *.jpg file format does use compression and therefore you should not edit your image, save it as a jpg and then re-edit and re-save it many times, because each time the file is saved it will be compressed and gradually the quality of the image will degrade.
Compression is the translation of data into a format that requires less memory than the original data.
When information is compressed,
- data may be discarded because it can be summarised, accurately, but more succinctly (“lossy compression”) and/or
- data may be unchanged but stored in a more compact way (“lossless compression”)
Lossy compression is like a book review. Lossless compression is like a squashed spring. A spring is exactly the same whether it is squashed or unsquashed. It just takes up less space, when it’s squashed.
Q. I want to edit my files at home before I bring them to you to have them printed, what should I do?
- Save the original *.jpg from your camera in a “non-lossy” file format; such as a Photoshop *.psd file or an uncompressed TIFF *.tif file.
- Do all of your editing on the *.psd or *.tif version of the file.
- When you’ve finished editing, save the final print version of your image to a *.jpg.
You should end up with 3 versions of the file, the original, the file you edited and the finished *.jpg, which is the one you send/bring to us for printing.
We can handle a vast array of digital image formats, from the common place to the old and unusual. If you think you’ve got something obscure or wacky, or if you’ve been told by other labs that they can’t print your files, or if you’ve got some images in a format that you can’t access yourself and you want them converted/printed, try us. We like a challenge.
Yes, please do.
This is especially helpful, if you’re e.mailing files to us.
We’d really rather you didn’t, because of the inherent security risks associated with *.exe files and because going through additional data security checks on the exe file increases our work flow.
Resolution is a measure of the amount of data in an image.
The higher an image’s resolution, the more pixels it contains and the greater potential it has to capture detail.
Low resolution is the main cause of poor quality prints.
Resolution is so important its got its own dedicated FAQ.
No amount of computer jiggery-pokery can add resolution to your images after they’ve been taken.
It depends on what you want to do; but, generally, the higher the resolution, the better.
MP stands for Megabytes. It is a measure of file size.
MP stands for Megapixel. It is a measure of image resolution.
Dots per inch. It is a measure of output resolution for printers.
Pixels per inch. It is a measure of resolution for scanners and monitors.
It depends on a lot of things, including
- the speed of your internet connection,
- the size of file(s) you are sending and
- how busy your Internet Service Provider (ISP) is when you are online.
Uploads take, at least, twice as long as downloads. Normally, on a 256kbs ADSL line:
- An 500 Kb image takes about 30 seconds and
- An 3 Mb image takes about 3 minutes
If you have 100’s of Megabytes of images that you want printed (or you don’t have broadband), you’d be better off to the bring them into the shop… unless you’re very, very, very patient or have the sort of bandwidth that would make NASA jealous.
It’s what happens when you cross lots of fairies and elves together; actually, no, hang on a minute, that’s still not right…
Pixelation arises when the individual pixels in an image are clearly visible to the naked eye. Pixelated images appear blocky. This is especially noticeable in areas that should be smooth curves, which appear stepped.
This flaw is caused by low resolution or too much compression.
Digital “noise” is the presence of unwanted colour pixels within an image.
Digital noise often appears as wayward green or red pixels in areas that should be a very dark colour, or as blue or purple pixels in areas that should be a very light colour. It is especially noticeable in areas of deep shadow or extremely highlights e.g. clouds.
Some digital noise is present in all digital images. The better your camera, the less noise it will exhibit. However, very obviously noisy images are usually the result of low light and incorrect ISO settings or some combination of the two.
Digital artefacts are areas of pixels which are incorrectly averaged, i.e. neighbouring pixels that are the same colour, when they should be subtly different colours.
Artefacts can be caused by post production manipulations or by too much image compression. The most common cause of digital artefacts is caused by repeatedly saving, editing and re-saving *.jpg files.
Adobe Photoshop is image editing software made by Adobe Systems Inc. It is the industry standard tool for image manipulation. It rocks, but it’s ludicrously expensive.
A shop where you get your photo stuff from.