Batch conversions

In past issues, this graphics column has covered a range of topics that relate to changing file formats and resizing. After a little practice, it can be easy to change only one or two images, but what about when the number increases to 10 or even 1000? This could become a time-consuming task and source of RSI, but, thankfully, it can be automated. The process of changing a collection of files is called 'batch conversion'. Instead of changing one file at a time, you merely set up the type of changes you wish to make, select the files that you want altered and the program will churn out the new images in no time.

One advantage of batch conversions when changing a collection of graphics files from one format to another is size differences: converting files from BMP to JPEG can save over 90 per cent of disk space. Then there may be instances when the dimensions of the image are important - a common requirement is to reduce a picture's size so that it can be easily downloaded off the Internet or sent as an e-mail attachment.

So, how do you run a batch conversion and which programs are best?

Paint Shop Pro has a simple batch tool. Photoshop has some novel features, but it can take a while to work out its peculiar methods and terminology. For those users who wish to battle with Photoshop's batch function, then select File-Automate from the menu. You will need to consult the manual for instructions, as the interface is far from intuitive.

The program that is simplest to use and loaded with extra features is IrfanView. Since IrfanView takes up only 0.4MB of disk space and is free, it makes a worthy companion to Photoshop or any other package. Not only does it convert file formats, but it will also apply cropping styles, create negatives, adjust colours, change file names and more.

After starting the program, go to the File menu and select Batch Conversion/Rename. Navigate to the folders where the files are located and select them. Then click the Add or Add All button, depending on your needs. You can add files from as many different locations as you want, but if you are trying this process for the first time, then remember there is no 'undo' in batch conversions. If you accidentally erase the files with their new versions, there is no going back. To avoid this problem, here are some tips to follow:l Create a new folder for your converted files - don't generate new files in the same folder as your originals. l If using Paint Shop Pro, check the box that says "Stop on error". This way, if you are about to replace accidentally a file with another of the same name, the program will stop.l When setting up a batch conversion, trial the process with just one image selected. After the batch operation is complete, open the converted file to ensure that the result is what you expected.

If you are converting files types, you will need to select the file format of the output file, such as JPEG, TIFF or BMP. Then navigate to the folder where the files are located. Select the files you wish to convert and click Add. Next, select your destination folder and make sure that there is enough disk space. When converting between file formats, you can tweak the conversion settings by clicking on the Options button. This can be useful if you are trying to improve the compression on TIFF or JPEG files.

For more experienced users, IrfanView offers a host of other choices, which can be selected by clicking on the Advanced Options button. The features here are quite powerful, so it is important to ensure that you pay careful attention to the choices you are making. Tread with care if you select "Delete Originals" or "Overwrite Existing files".

Another handy feature listed in Advanced Options is the resize feature. This can be useful for reducing larger images, or creating slideshows or desktop images where the pictures all need to be a similar size. When resizing, ensure that you check the box labelled "Preserve Aspect Ratio", otherwise your images will be skewed in one direction. For better quality, also check the option "Use Resample function".

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Scott Mendham

PC World
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