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The parametric workflow

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The parametric workflow compared with a traditional JPEG workflow

 

The figure below illustrates the processing made by the ASIC (Application Specific Integrated Circuits) in the camera when creating a JPEG. It's no small feat, obviously...

 

We can make several observions about the signal path. One observation is that there are several points in the processing pipeline where information is lost or artifacts can be created:

  • The demosaic stage normally can introduce moiré patterns or loose sharpness
  • Color interpretation uses color temperatureas input, once this is applied some colors are irrevocably lost
  • Sharpening can add artifacts
  • Conversion to a small color space throws away colors falling outside that color space

It's also obvious that a single JPEG cannot fit all purposes equally well.

  • For print we need a high resolution image with pretty agressive sharpening and preferably a large color space.
  • For WEB we need low resolution images, probably in sRGB color space.
  • Slide show may represent a different challenge.

The parametric workflow

In the parametric workflow we keep the original image and have a "recepie" how to process it. So the image is only rendered on the fly when needed.

This has multple benefits:

  • All information from the original image is kept
  • Output can be optimized for the actual purpose
  • The original data are much more compact than any of the normal formats used for processing images, like TIFF or PSD.
  • If better methods are developed for handling the raw image, these methods can be applied at any time
  • There may be different recepies for a single image

Digital Asset Management and parametric workflow

DAM and prametric workflow are not really related. On the other hand, the same companies that invented the parametric workflow also have choosen to integrate parametric processing with DAM functionality.  As it happened the first product having parametric editing and DAM capability was Apple's Aperture. Adobe was at that time developing something called Shadowland, but was not really enthusiastic about introducing it to the market, possible because they assumed that it could cannibalize sales of Adobes Photoshop product. The introduction of Apple's Aperture caused Adobe to turn around and release Shadowland to the public as the first "public beta' of Lightroom.

Can parametric workflow replace Photoshop?

The asnwer is both yes and no. Parametric workflow is not a "pixel level thing". At present a lot of things are missing at least from Adobe Lightroom, like correction of distortion or keystoning. These could be added quite easily, the reasons that it has not been done are probably  "political", Adobe wants us to buy Photoshop. There may be other alternatives to Lightroom and Aperture, like the new promised version of Bibble Pro.

  • DxO Optics Pro has much of what is missing from Lightroom. Kan correct chromatic aberration, distortion and keystoning but lacks essential DAM capabilities. It's also more of a traditional raw-converter producing TIFFs than a parametric workflow engine.
  • Bibble labs Bibble Pro 5.0 will be a challenger when it reaches a usable release, it does add early stage correction to the pixel processing pipeline, layer based parametric edits and DAM capability.

What's wrong with TIFFs?

Any raw converter can produce TIFFs, what's wrong with TIFFs? Actually quite a lot!

 

  • TIFFs are fat. Raw files have 12 or 14 bit's information for each pixel, TIFFs need 48 bits of information to hold exactly the same data.
  • TIFFs are normally intermediary files. so if yo change the TIFF you also need to change all your edits. If we assume that we work in  Lightroom:
    • We need to re export the file
    • We need to reopen it in Photoshop
    • We need to repeat all our edits
    • We need to re save the file
  • In Lightroom we just move the slider. We still need to regenerate our slide show or webpage, but don't need to start Photoshop and do extensive edits.

Advantages and disadvantages of different workflows

The in camera based JPEG workflow

Advantages:

  • Fast minimal work
  • Supported by really good hardware
  • Careful about resources

Disadvantages:

  • Information is lost, no way going back
  • Good but not optimal
  • Esy to make really bad mistakes

Parametric workflow

Advantages:

  • In a sense optimal. All data available all the time,
  • Actually quite good efficiency reagrding storage place.

Disadvantages:

  • More work, shooting the pictures is half the effort.
  • You need to decide what colours you want. How green is the grass?

 

 

 

 

 

 

 

 

 

 

 

Last Updated on Wednesday, 16 June 2010 21:40  

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