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SilverFast Ai & HDR

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Tutorial - 6

Colour Management Explained

By Ian Lyons

A Computer Darkroom Review

SilverFast features many advantages over the OEM scan applications supplied with many of today's scanners. However, to ensure that we can make best use of these features in our workflow we need to understand the approach adopted by LaserSoft when managing colour.

 

SilverFast Ai and HDR and Colour Management

SilverFast differs from many of the free offerings from vendors such as Canon, Epson, et al in so far as colour management is at its core rather than an after-thought that really does little more than squeezes our images into the sRGB colour space. On the other hand SilverFast incorporates two important colour mangement functions:

  1. Automatic colour matching with Photoshop to ensure that what you see in SilverFast is what you get in Photoshop

  2. An integrated IT-8 calibration module (optional extra) or scope for assigning a third party custom scanner profile. Both methods ensure that SilverFast has match the colour rendering characteristics of the scanner.

The following is a short explanation of the various possibilities for configuring the SilverFast Colour Management Settings (CMS) dialog. The settings shown are compatible with SilverFast 36 to 24bit colour, 48 bit colour or HDR colour modes.

The CMS window has four separate sections which are used to determine the extent to which SilverFast will manage the colour of your images. These are:

  • Colour Management - In this section we define whether and/or how SilverFast will integrate with the PC operating system and image editing applications such as Photoshop.

  • Profiles for ColorSync/Image Colour Matching - In this section we select the various Input profiles (scanner/camera) and Output profiles (e.g. Photoshop working space) .

  • Embedded ICC Profiles - In this section we decide whether to enable profile embedding. Remember that embedding an ICC profile is the means by which other applications can decode the colour recipe used when previewing and editing our images in SilverFast.

  • Plug&Play CMYK - This section is only relevant when the user has chosen to export scanned images in CMYK.

Example 1

Image

Using the above settings mean that SilverFast will NOT manage the colour of  your documents and NO profile will be embedded within the document. Furthermore, the document previewed on your display is unlikely to match that which finally appears in Photoshop.

Example 2

Image

As with the previous example you are instructing SilverFast to NOT colour manage our documents. However, in this instance you're embedding an ICC profile that describes the scanners colour rendering characteristics. So we could describe these settings as providing a function "similar" to the Assign Profile in Photoshop 6, 7 and CS. Again, the preview display will NOT be a true colour representation of how the image will appear in Photoshop.

For normal scanning the settings described in this example are NOT normally recommended.  However, by  embedding the scanner profile it does at least provide colour savvy applications with some knowledge as to how the document should appear. It is also one of two possible CMS configurations when scanning for archive purposes. The other method is described as Configuration for User Group 1 in the HDR High Bit scanning tutorial to be found here.

Example 3

Image

As with the two previous examples we're still NOT colour managing in our images. The absence of a scanner profile means that we have no way of describing the source colour characteristics of the image, and so these settings again correspond to the Photoshop 6, 7 and CS Assign Profile command. However, in this instance the embedded profile is the Photoshop working space profile. The choice of Automatic for "Internal -> Monitor" and  your Photoshop working space profile for Internal (Profiles for Image Colour Matching/ColorSync) means that we get an accurate preview. The settings shown example 3 are probably the best choice for users without the luxury of the SilverFast IT8 Calibration module or a custom scanner profile.

Example 4

Image

The settings shown for example 4 indicate how SilverFast should be configured when we require a FULLY colour managed workflow.  The "Input -> Internal" = ColorSync/Image Colour Matching instructs SilverFast to use the IT8 calibration profile as the source with whatever profile we have selected in the Internal (Profiles for ICM/ColorSync) as the destination colour space.

Typically the Internal profile will be the same colour (or working) space as we selected in Photoshop The choice of Automatic for "Internal -> Monitor" ensures that the preview display accurately reflects how the image will appear in Photoshop and with the Calibration profile in place we are assured that the colours being displayed are a close rendering of the original. The "Internal -> Monitor" should be set to Automatic so that an accurate preview display is assured.

Note that with example 4 we embed the Internal profile or as it should more correctly be called our "working space profile" into the image. To avoid any ambiguity the Internal colour space profile is that associated with Photoshop and NOT SilverFast. In the example shown above I selected Adobe RGB (1998) since this is my preferred Photoshop working space. Given that we have a source and destination profile we describe these settings as being "similar" to the Profile to Profile command in Photoshop 5.x or Convert to Profile command of Photoshop 6/7 and CS.

Important!

The KEY point to note between example 4 and that of the previous examples is the impact of simply choosing something other than None in the Input -> Internal field. The Input -> Internal field is effectively the switch by which we turn colour management ON or OFF. None means colour management is OFF. ColorSync/Image Colour Matching means colour management is ON.

Example 5

NegaFix Special Case

A further enhancement introduced recently is that SilverFast will ignore the Input profile selection when the user chooses to scan negatives. The really neat thing about this change is that unlike previous versions of SilverFast the user need NOT make ANY changes to their default CMS dialog configuration. Choosing the setting shown in example 4 above and having set SilverFast for scanning negatives results in the Input profile being automatically disabled. However, in order that the SilverFast preview and Photoshop display of the scanned image are matched we should still ensure that our current Photoshop working space profile is set in the Internal (Profiles for ICM/ColorSync) field.

Image

The above settings apply equally to 36 to 24 bit colour mode, 48 bit colour or HDR colour mode.

 

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