Frequently asked questions – Digital files
Q: How do I find out the size and other information about a file?
A: (Windows pc) In Windows explorer, right click on the file icon and choose ‘properties’ at the bottom of the list.
(Mac) (In finder, ctrl-click on the file and go to ‘get info’ in the file menu (or shortcut command ‘i’).
Q: When I email a photo it takes a long time to send. Why is this?
A: This is usually because the file is too large. Check the properties of the file (see above) and resize the file to a more suitable size for emailing.
Q: Why do we need to make photos smaller?
A: It is good practice to make image files smaller whenever possible. Otherwise they will use excessive space on the computer hard drive or server where they reside. Often files can be reduced considerably in size with little noticeable effect when viewed.
Q: What is a bitmap?
Bitmap (or raster) file) are made up of pixels and tend to be photographic images. See section on bitmap files in the blue section. Also see bitmap in the glossary.
Q: What is a vector file?
Vector graphics files consist of geometrical elements such as points, lines, curves, and shapes or polygons, which are all based upon mathematical equations, to represent images in computer graphics. See section on bitmvector graphics files in the blue section. Also see vector in the glossary.
Q: How do I make a file smaller to save space?
A: The file needs to go through processes of resizing, resampling and compression. See the orange ‘how to’ section where you fill find further help.
Q: What is batch processing?
A: This refers to the process of creating a specific processing task on a group of files rather than just one. This will obviously save a lot of time if a group of files can be processed at once.
Q: I have a photo which is not very good when printed or viewed on screen. Can I make it better quality?
A:If at all possible you should try and find the best quality image ith the largest pixel dimensions. If that is not necessary you can try the process of upsampling as a last resort. Some software programs are able to improve an image quality by adding pixels (through guesswork and looking at the nearest neighbouring pixels to work out what is required). This is known as interpolation. Upsampling is not always successful but worth a try if there is no other option. See the orange ‘how to’ section on resizing.
Q: What is the best way of transferring photos onto my computer?
A: There are several possible ways of doing this. A usb cable can be connected between the camera and computer. Special software (which has usually come with the camera) can be used to select and transfer the images to a folder on your computer. Alternatively, the camera memory card can be removed from the camera and inserted into a memory card slot in the computer or via a usb memory card adapter. The memory card can then be browsed and selected photos can be copied and pasted directly to the computer (or via software).
Q: What’s the best way of storing my photos on the computer so I can find them easily?
A: There are many software applications available which will store and catalogue your photo collections so they can be browsed and searched easily. Picasa (freely available as a download from Google is one example of the many available. They often provide simple editing tools for improving your photos as well as easy ways to resize, send by email or upload images to web pages.
Q: Can I make a vector image into a bitmap?
A: Yes, a vector image can usually be exported to a bitmap format such as jpeg or tiff. This process is known as rasterisation where the vector elements (lines and fills) are converted into pixels. The lines ane fills of the vector will no longer be editable, because the bitmap file will become one image. The only way of editing the image would be through a bitmap-editing software application such as photoshop.
Q: Can I make a bitmap image into a vector?
A: Yes, this is possible, though not straightforward. The bitmap image would need to be imported into into a vector program. The next stage would be to ‘trace’ over the image (ie. drag over the image with the vector trace tool) to create lines and fills. Sometimes this can be quite successful but it can be a case of trial and error and the image is unlikely to be identical, especially if there are subtle tonal changes in the image, which vector files do not handle well.
Q: How do i change the shape/proportions of an image?
A: This is easily done through photo-editing software. See the ‘Crop an image’ movie clip in the orange section.
Q: How do I brighten a photo which is too dark?
A: Photo-editing software allows you to do this. See the ‘Brighten an image’ movie clip in the orange section.
Q: Can I change a colour photo into black and white?
A: will be in RGB mode which is full colour. Change the mode to ‘grayscale’ and you will be asked if you wish to discard all the colour information in the file. Click ‘yes’ and proceed. The image will become a monochrome black and white image. Remember to save the file with a new name if you want to keep the original colour image as well.
Q: What is resampling?
A: This refers to changing the pixel dimensions in a bitmap image. Downsampling means reducing the number of pixels (width and height) to reduce the size, while upsampling means increasing the number of pixels (width and height) through interpolation to increase the size of the image. See ‘Resolution explained’ in the blue section.
Q: What is a good size for a photo to send by email?
A: This depends on what the emailed file is going to be used for. If it is just to view on screen an an image size of around 400 x 600 pixels will be good enough for viewing on screen. Larger files can be emailed but will take slightly longer to send (depending on the speed of the inernet connection).
Q: What is a good size for a photo for a powerpoint presentation?
A: The answer is similar to above as the image is for viewing on a screen and is unlikely to be printed. Image pixel dimensions should be at a resolution of around 400 pixels or more at 72 pixels per inch to get a reasonable quality image. It does depend on how much of the screen the individual image is going to use. If it is a small image in a corner it could be made smaller to save space, or bigger, to improve the quality, if it is going to fill the screen
Q: What is a good size for a photo to be printed?
A: For printing, image sizes need to be larger, in fact as large as possible to get the best result from your printer. Print from the best quality you can, at least 300 ppi if possible and the maximum pixel dimensions you can get from your camera.
Q: What is a good size for a photo to go on a website?
A: The answer is similar to that for images for powerpoint because the image will be viewed on a screen. It depends on how much of the screen the individual image is going to use and also what the screen resolution is likely to be. Common screen resolutions are 1024 x 768 pixels but some people still use smaller screens. Therefore if you upload an image to the Web that is 1800 pixels x 1200 pixels it will not fit on the screen. Therefore choose something appropriate such s 600 x 400 and then the file is likely to fit nicely on all screens. If it is a small image in a corner it could be made smaller to save space, or bigger, to improve the quality, if it is going to fill the screen. Image pixel dimensions can be anything from a resolution of around 100 pixels or more at 72 pixels per inch. If the image is qoing to be available for printing it is good practice to save this as a separate link on the web page, stating that it is a larger file which will take longer to download.