Permalink22 February 2007 at 13:25 by Alan Capel - Head of Content
Posted under Boring but necessary announcements, Advice and tips
© Brand X Pictures
Our required file size for submitting Jpegs seems to cause an incomprehensible amount of confusion with a high volume of photographers. Put simply, we are flabbergasted as to how many times we are asked, daily, of what format and size of images we require!
Let’s set the record straight right now. First and foremost, yes, we want you to send Jpegs. No, we don’t want you to send Tiffs. The reason for this is that we provide our clients with Jpegs to download, not Tiffs. It’s been industry standard to work like this for a long time now and even in the days when we required you to send us Tiffs, we converted them to Jpeg for the clients. Yes we know Jpeg is a lossy format, but to the naked eye, there is no visible difference between a high quality Jpeg and a Tiff file. The client can simply download the Jpeg, save it as a Tiff, and work away on it saving as many times as they like without loss in quality. It’s really that simple!
Now that’s out of the way let’s move onto file size. Jpeg is a compressed file format. The compressed file size (size on disk) varies with picture content and should be ignored, as long as it’s no bigger than 25MB, which is our upper limit for Jpeg size. What’s important is the uncompressed (opened) file size. The opened file must be at least 48MB at 8 bit to get through our quality control. Typically a 48MB 8 bit file will be between 3MB and 10MB as a Jpeg if your image was shot digitally. Film scans will be larger. This is because Jpeg “sees” film grain as image detail and compresses it too. You can easily exceed 25MB from a 35mm film scan saved at Jpeg level 12. It’s sometimes necessary to save at Jpeg level 10 to get below 20MB. Yes we want you to send us the Jpeg. No we do not want a Jpeg 48MB in size as yes that would be ridiculously large!
What you don’t want to do is work on your images whilst they are in Jpeg form, repeatedly saving as you go along. Saving a Jpeg as a Jpeg is pretty much a no no, as you are recompressing a compressed file. An ideal workflow example would be to convert your image into a Tiff file, upsize it to a minimum of 48MB at 8bit, make any alterations as needed with dust spotting, levels etc then at the very last step, save as a high quality Jpeg. Yes, we want the Jpeg!
We found this very interesting article on Jpegs through Wikipedia that you may also find useful.
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