Special Considerations for Live Picture Separations

Those of us who have discovered the benefits of using Live Picture have often become frustrated with using Live Picture's separation control and as a result never utilize the superior separation engine in Live Picture. There is a certain disadvantage after-the-fact with Live Picture being unable to manipulate individual chanels and do CMYK color editing directly. Thus it often becomes necessary to utilize Photoshop for fine tuning separations after conversion even when mode changes in Live Picture are superior. In the section that follows I hope to outline the steps required to bring files into and out of Live Picture acurately and to translate Live Picture's look-up tables into Photoshop tables effectively.

In order to make Live Picture cluts available to Photoshop we have to be able to build files out of Live Picture with pixel for pixel accuracy in terms of file size. Use the following procedure whenever you need to maintain the original pixel dimensions of a file-- I am using the Photoshop Lab Colors file because we will be using this later to build out for a Photoshop look-up table. ( you will have to convert the PS_RGBcolors.Tif you save out of Photoshop to an IVUE or FlashPix file before you can follow along with these steps )

Insert Image at 100% and build out at 100%

  1. Open Live Picture and go to: File--> Document Setup... set the resolution to the same as the original file ( in this case 72 dpi ), make sure Define Initial View is unchecked and click new-- other parameters are less important, just make sure you don't define the document too small in inches as this complicates things a little bit later on.
  2. Go to: View--> Auto View , make sure auto view is checked
  3. Go to: Create--> Image Insertion, now in the open dialog make sure you DO NOT HAVE Auto Insert checked and open the file
  4. In Positioning Mode type in 100% in both height and width for scale and hit enter.

    When you switch to creative mode you will now have a view for the exact pixel dimensions of your original file.
  5. When you build out to a Tiff file make sure you sellect the view with the title of your original file ( the auto view created when you inserted the image ) and build out to 100%

You can use this procedure anytime you do not want the files size to change at all during build out. As it turns out we have to make an exception when building a file out for use as a Photoshop separation table

Special requirements for bringing LP tables into Photoshop

  1. Because Live Picture always adds at least 0.5% noise to build out files ( even when you have set noise to 0% in the build dialog ) you must follow these steps when building out a CMYK Tiff file for use as a Photoshop separation table.
  2. Instead of building out at 100% ( as in step 5 above ) build out to 400% make sure anti-aliasing is unchecked and noise is at 0% . Give the file a name descriptive of the separation settings (i.e. LPdefaultRGBtoCMYK.tiff )
  3. Open this new Tiff file in Photoshop and do: Image--> Image Size... set scale by percentage in height and width to 25% and check to see that new image size in pixels matches the original file size(W=363, H= 99) make sure you have interpolation method set to Nearest Neighbor
  4. Save the file in the Raw format using the following dialog box settings: File Type: 8BST, File Creator: 8BIM, Header: 0, Save Image In: Interleaved Order ( see step 6. in creating a clut for RGB-to-CMYK for use in Photoshop )

This procedure will average out the noise introduced in Live Picture's build and give you a usable file for your Photoshop table. You will use a similar procedure for creating the CMYK-to-RGB table. Here the actual conversion to RGB from CMYK happens when you convert the Tiff file to IVUE or FlashPix.

  1. In Live Picture open the CMYK colors file from the converter menu and make sure the lookup table you want to use is loaded in the separation control dialog ( you will have to have a fits file open inorder to do this )
  2. Save as.. IVUE, make sure that Adapt Separation Table.. is not checked and give the file a descriptive name (i.e. LPdefaultCMYK-RGB.ivue)
  3. Create a new document ( as in step 1. of Insert Image at 100%... ) with resolution of 72 dpi and insert the new IVUE file with an auto view at 100%
  4. Build out to an RGB Tiff file at 400% ( as in step 2. above ) with noise at 0% , anti-aliasing off and name the file appropriately (i.e. LPdefaultCMYK-RGB.tiff )
  5. Open in Photoshop and scale to 25% ( as in step 3 above ) using Nearest Neighbor interpolation in order to average out noise.
  6. Save the file in the Raw format, using the same dialog box settings shown above ( see step 5. of creating a table for CMYK-to-RGB. )

You now have usable tables for Photoshop and once loaded you can save a bi-directional table that can be used whenever you want to view Live Picture separated images in Photoshop or convert RGB files using this Live Picture clut. It is worth pointing out here that even if you use Live Picture's look-up table in Photoshop the results will not be as good as if you converted in Live Picture. Live Picture calculates its conversion in a 48 bit color space and will not suffer as much from round off errors in the calculation. This is most noticable in blends and gradations which will be more linear and free from banding. However good the Live Picture conversion is there is almost inevitably some correction necessary after the conversion and this is where it is quite helpfull to bring the file into Photoshop for final tweaking, unsharp masking and otherwise preparing for output. Having the appropriate clut available to view LP separated files in Photoshop makes this last tweaking step much easier.

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