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JPEG v RAW Ian Thompson ARPS

JPEG v RAW Ian Thompson ARPS. BEACON CAMERA CLUB Beginners’ and Improvers’ Group. JPEG. J oint P hotographic E xperts G roup Created in 1987, way before digital cameras Designed to produce small files Storage was expensive then! Variable ‘lossy’ compression

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JPEG v RAW Ian Thompson ARPS

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  1. JPEGvRAWIan Thompson ARPS BEACON CAMERA CLUB Beginners’ and Improvers’ Group Beacon Camera Club

  2. JPEG • Joint Photographic Experts Group • Created in 1987, way before digital cameras • Designed to produce small files • Storage was expensive then! • Variable ‘lossy’ compression • 8 bits (256 levels) per pixel per RGB • Alwaysloses data! Beacon Camera Club

  3. ‘Lossy’ Compression • The detail in the image is analysed and various bits of it are discarded. • This analysis produces a different result each time and different bits are thrown away on each edit. • When opened, a similar arbitrary process occurs, so the resultant image will be a tiny bit different on each opening Beacon Camera Club

  4. Quality choice • Quality (amount of compression) can be chosen between ‘good’ and ‘awful’ Beacon Camera Club

  5. 5 Edits Original 10 Edits 20 Edits Editing Degradation • Images degrade every time a file is edited even if just 1 pixel is altered! • The effect is worse for high compression but still applies to low compression (high quality) • Impossible to recover detail from highlights or darks during editing Beacon Camera Club

  6. Can We Do Anything? • Very Little. This is a fault with JPEG images, the spec was designed long ago • Degradation can be reduced by working with JPEG images that are multiples of 16 pixels wide/high… • …because the compression algorithms work on image ‘blocks’ of 16 x 16 pixels • Convert to lossless TIFF before editing Beacon Camera Club

  7. So, why use JPEG? • To post images on websites • To print ‘straight from camera’ • For use as small images in brochures, etc. • OK for bigger prints after one edit • JPEG is an archaic ‘convenience’ method which prevents you getting the full quality that can be provided by your camera! Beacon Camera Club

  8. RAW images • RAW is just that – unmodified sensor data • Nearly all cameras produce RAW images • Files will be large - storage is cheap • NO lossy compression – all data is kept • 12 or 14 bits (4096-16384 levels) per pixel per RGB • Best chance for a good output image Beacon Camera Club

  9. RAW images • What you see on the camera’s LCD is a jpeg representation of the ‘mode’ chosen • The ‘mode’ is a recipe applied to the RAW image – the RAW data is unchanged • A RAW file is like a digital negative – you cannot alter it…. • ….meaning that this is a really safe file: editing won’t lose the original Beacon Camera Club

  10. RAW images • Workflow is different to JPEG editing 8 bitJPEGfile Editor 8 bitJPEGfile Original can get over-written! ‘Style’ alreadyapplied JPG, TIFF,GIF, PNG, etc,NOT RAW! (WHICH CANNOT BEOVER-WRITTEN) Outputfile 12/14 bitRAWfile 16 bitRAWconv. Editor RAW sensordata ‘Style’ applied Beacon Camera Club

  11. RAW images • If I don’t have Photoshop, how do I handle RAW files? • Use your camera’s bundled software to create a 16 bit uncompressed TIFF • ..then you will NEVER lose your original! Beacon Camera Club

  12. JPEGv RAW FOR: • Huge tonal range – 12-14 bit • Cannot overwrite • ‘Lost’ detail can be recovered • Data never lostas long as JPEG not used for ‘save’! AGAINST: • Large files FOR: • Small files AGAINST: • Data loss on each edit • Poor graduation of tones – 8 bit Beacon Camera Club

  13. JPEG V RAW • The biggest difference is that a RAW file will have 64 times more resolution in the graduation of tones • This means that your skies and skin tones will look and print smoother • If you convert a 16 bit RAW file to JPEG, you will compress those tones by 256 X Beacon Camera Club

  14. Sub-directories for RAW files Image Editing Software • First, a suggestion for file management.... ….because most people lose files at some point! Your data disc (probably not C: !) Top Directory Photographs 2016-06-25 Aunt Aggie’s 60th 2016-09-13 Tenerife Work in Progress EDITS JPG, TIFF, etc. Output files Other directories… Other directories… Beacon Camera Club

  15. Image Editing Software • Many, many programmes…. • Cheapest – Windows Photo Editor – Free! No RAW 8 bit • GIMP – Open source FREEware – R, mostly 8 bit • Photodirector 4 – <£40- R 16 bit • Corel Paint Shop Pro – R 16 bit • ArcSoft PhotoStudio - £39.99 - R 16 bit • Photoshop Elements- approx. £50 - R 8 bit • Adobe Lightroom - £73 – R 16 bit, but not a pixel editor • ..or Photoshop + Lightroom - £8.50 per month - R 16 bit ….and you get pretty much what you pay for R = RAW accepted Beacon Camera Club

  16. THAT’S IT! Beacon Camera Club

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