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Why you can't just 'shrink' a JPEG
Following a recent discussion on a forum which consists of mostly PR people, I was shocked to hear the treatment various PRs have at times given photos to make them suitable for email and publication - with no real regard to the effect the various treatments will have on the final image and image quality.
People were using a variety of applications such as Word, Picasso or Paint to ‘shrink’ or resize JPEG photos in an attempt to make them smaller.
Three basic facts you need to know
There is a need to understand three basic facts here:
• Each photo has a physical size measured in millimetres or inches and a resolution measured in pixels or DPI (Dots Per Inch). Roughly speaking, the more DPI, the higher quality the print will be – this would generally be a minimum 300dpi for printing or 72dpi for online use. Ideally you would select the exact size and resolution each publication needs, but this is impossible to know so you must choose a catch all size to give each publication the choice of how large they wish to use the image. Of course, the larger the physical size or resolution of the image, the larger the file size will be. Another general rule is that one never increases the dimensions of a photo, as this would decrease the image resolution and diminishes the quality. So our ‘catch-all’ standard media size for images destined for media print use is 8 inches (or 2400 pixels) on the longest side at a resolution of 300dpi.
• JPEGs are created using a compression algorithm which can be adjusted to provide an image in a small file size where the quality will be poor or a large file size where the quality will be exceptionally good. The trick is to use the correct setting the first time the image is saved to ensure the photo is fit for purpose. The JPEG format is a ‘lossy’ format so as you go closer to the small file size/low quality end of the spectrum the more of the image information is lost. And this loss is permanent each time you save the file, so experimenting by saving the file over and over again to get the most suitable file size means more and more information and image quality is being thrown away each time. On the scale of 1 being poor quality/high compression and 12 being highest quality/low compression, we use 11. This reduces the file size substantially, but ensures the time and effort in creating the perfect press photo is not thrown away too.
• The colour model used in the JPEG image is important. Generally for media use and print where a designer is going to be involved in using the image, it is best to supply the image with a colour model that provides a wide colour gamut such as Adobe RGB. If the image is destined for online use, then the sRGB colour model should be employed making the image look more vibrant on a computer monitor/tv screen.
Take care not to make the picture useless
Given that a typical news release is generally 50% words and 50% picture, I believe far more care should be taken to ensure that the photo is a suitable size, using a suitable colour model, and saved (ideally just the once) using the correct JPEG compression ratio. Many picture editors cringe at some of the photos they are sent for publication. And those photos will never get used. Given that the photo makes up such an important part of the news release, you can bet the PR’s client is paying for the photography in the belief their PR knows what they are doing.
Of course the need for the PR, who in the main is an expert in words not pictures, to adjust the supplied photos should in fact be totally unnecessary - given that the photographer who originally supplied the images should have supplied them in formats suitable for the purposes they were required, and to cover all bases.
For example, by default, we supply each retouched image in two formats: a size suitable for standard media use, and a smaller image sized for online/web use with appropriate colour models - to ensure the image will display at its best given the final display medium.
If your photographer isn’t doing this, ask them why not. Or talk to us next time.
Written by Simon Apps, ex-press photographer and
founder of Professional Images. Professional
Images are specialist PR
photographers providing PR, press and editorial photography to PR consultancies and press offices.
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