Never use JPEG in your workflow
JPEG’s save space, allow faster loading, processing and ripping, they also give good colour reproduction, so why should you never use JPEG’s in a print workflow?
JPEG’s are possibly one of the biggest pains in reprographics. Next to LZW Tiff files they cock up more ‘quality’ jobs than any other file format and believe us over last 30 years of digital reprographics we have seen hundreds. Many of today’s brochures and magazine use JPEG’s quite successfully. They have numerous advantages over other file types, which is why they are so common. But in the wrong hands they will ruin any job.
Compared to a PSD or Tiff file, JPEG’s are lower quality. You can more or less always tell that a particular image was saved as a JPEG because in areas with strong contrast you can see compression artefacts. The stronger the compression the more JPEG noise or artefacts. Most other file formats use lossless compression. These files are larger than JPEG because they use a fully recoverable (lossless) compression that preserves all of the original image data. These file formats offer full quality at all times, no matter how many times they are saved.
This is why you never use a jpeg
JPEG compression algorithm changes image data while converting it. Amount of change can be controlled, but not its location which is always noticeable around sharp colour changes and across gradient areas.
JPEG FILES WORK BY THROWING AWAY DATA. THIS DATA CANNOT BE REPLACED – EVER.
If you use JPEG’s in your workflow then somebody, at some point in the future is going to use this file incorrectly. They are going to increase its size to save time, they save again reducing further the quality. While many JPEG’s, even poor quality ones print ok, do you really want to loose a customer because of an error than can be avoided simply by using a better quality workflow?
JPEG general information
- JPEG is primarily an RGB format.
- It is also fine for print but beware it’s pitfalls.
- If you save a JPEG image several times, you’d end up with an unusable image. Because every time you save you throw away even more data. Photographers always make the mistake of saving their JPEG file again, thus giving the end user an inferior file to their own original.
- JPEG’s cannot be restored to its original.
- You can remove some compression artefacts in Photoshop.
- In print always save JPEG at the highest possible quality and set to baseline standard.
- For web save at Quality 8 or 10 progressive. Remember this image should be optimised when in your chosen app.
When to use JPEG
If you are processing 100’s of files every day, JPEG’s being a smaller file offers a credible and faster solution. It is deciding when you can use a JPEG and when not.
Newspapers are typically printed in a resolution of 85 lpi, while some magazines may print at 133lpi or 150lpi. At these lines per inch even poor quality images print reasonably well. If you are producing in a hi end magazines or brochures for printing at 200lpi or stochastic printing, quality is everything and poor image will be noticed especially against a quality image.
TIFF general info
- TIFF is best file format for printing
- It’s perfectly natural for a TIFF file to save image data in CMYK colour space which is used in press.
- TIFF can also compress image data but uses such an algorithm that doesn’t change source data (lossless compression). But please do not use this option.
- TIFF format also supports alpha channel (transparency).
- If you’d be opening and saving the same TIFF file, you’ll end up with exactly the same image as source. Nothing would change in terms of image data.
There is nothing inherently wrong with a JPEG file if you know what you are doing. But when it comes to your print workflow RAW, TIFF and PSD files are far superior. Unlike 20 years ago when disk space was at a premium today, there is no excuse in compressing files. Terabyte storing and large format transfer means that 300mb files are common place.
Pre Press recommend that your master file should be 400dpi at original size supplied as an RGB. Covert to CMYK if you need. If you understand ICC profiling then add this, if not, switch all colour profiling off.
If you want your images to stay as true to original as possible save with PSD or TIFF file format. This PSD file format can be used in all page make up programs including InDesign and Quark with no problems. If you prefer a TIFF file format that also is fine and our preference. However DO NOT SAVE WITH LZW COMPRESSION these files will often give unexpected print results – you have been warned.
Images for print
- Save as PSD or Tiff with no compression
- CMYK as colour mode
- A minimum of 350dpi at 100% for 200lpi
- A minimum of 300dpi at 100% for 150lpi
- Colour settings are normally FORGR39. Check with your printer
Images for web
- For images JPEG
- Recommended 72dpi
- Switch colour settings off
- Logos and other graphics we recommend the PNG file format
Images for large format
- RGB or CMYK*
- Images PSD or TIFF or EPS
- Recommended 300dpi at 25% minimum
- Switch colour settings off or use FOGRA39. Check with your printer
- Ensure that your photograph is taken at the highest resolution possible. and save at 400dpi. Why this high?, Rule of thumb is twice the dpi to the lpi. 300dpi is suitable for presses that run screen of 150lpi. These days most good printers use 200 line screen which need a higher resolution – hence 4oodpi. Also you many need to use this image again for large format work. So with have one master file for everything or several files at the correct size.
- All photography should be taken and supplied as RAW files. Note Photoshop will open these as 8bit files only, you have to tell it to open at 16bit.
- The advantages of 16 bit files are clear to see. Better gradients, better shadow areas, more control and a dam sight quicker to put a clipping path around an image.
- Insist that your Photographer supplies RAW files only.
- Ask your printer for help or even a specification guide.
- Ensure you understand how to correctly make a PDF, Remember when making a PDF it compresses images.
- The name “JPEG” stands for Joint Photographic Experts Group, the name of the committee that created the JPEG standard and other still picture coding standards.
- Remember if you supply your image too small it will print badly.
- If you supply a image that is too large it will print perfectly.
* Note printing RGB images on large format printers offer a far larger colour range than CMYK
This FAQ was first written April 1999. Updated 2005/2014/2020