Hello all, This is the folow-up to my previous message, in which I praised the negpos plug-in to invert negatives. In this message I will outline my negpos workflow. It is based on just a few days of experience, so it might not be perfect yet. Even so, for those interested it might give a good starting point to get the most out of the plug-in. This workflow is aimed at batch scanning a whole roll of negatives. At certain points I will refer to the Minolta scanning software, as this is what I use with my Elite 5400. Even so, it should be applicable to other scan software as well.
1. Set the scan software to produce linear 16-bit scans. [In minolta scan: set 16 bit linear. Any mode, negative or positive will do, but negative gives finer exposure control] 2. Take an empty leader or trailer image. Adjust the exposure such that the empty negative is almost overexposed, but the total distribution remains visible. (This is not a critical step, but it is used to optimally use the dynamic range of the scanner � it�s only useful if the exposure is a *hardware* control.) [In minolta scan : in negative scanning mode, this means clustering the histograms towards the left. Save the exposure settings under the film roll name. Separate exposure settings are usually not needed when ICE is enabled. The rest of the procedure should be done separately for scanning with and without ICE.] 3. Scan the empty image as a black reference. 4. (Batch) Scan all the pictures using the same exposure settings. 5. Next, open photoshop: 6. Open the reference image in a neutral editing space (R=G=B implies grey) and locate the median location of the film base peak using the histogram (PS CS). Write down the RGB values. 7. Open a representative image from the same roll into photoshop and open the negpos window. 8. For the shadow tail, enter the median values found in the reference image and set the blackpoint setting to �tail�. In the �Gamma C� box, enter the gamma of the profile you have assigned to the image. If you selected �don�t color manage�, use the gamma of your working space. In the other �Gamma� boxes on the bottom left, enter the appropriate numbers for the film type you�re using � see also the list at the end of this post. 9. For the other parameters, use whatever looks best. A good starting point is to use equal perecentages in the RGB boxes of the shadow, highlight and highlight tail columns. Then adjust the highlight settings until the grey balance is correct. Note that negpos only controls the grey balance, not the intensity of any or all colours. This should be done afterwards, by assigning a different profile or adjusting curves etc. It�s like selecting a different type of film and has little to do with the processing as such. 10. Uncheck �ex by %� and run negpos. This will cause subsequent images to be adjusted with the exact same setpoints instead of percentages. 11. In the ideal case, simply apply the negpos filter to all other images in the same roll. This uses the same settings for every image. In practice you will often use the above settings as a starting point for further tweaking. A save/load option in negpos is sorely missed� In step (8), one has to enter the inverse gamma values for the film type (for an explanation, see the documents on http://www.c-f-systems.com/PhotoMathDocs.html and the manual). I quickly measured some response curves from the data sheets of the Fuji film types I�m using. The values are listed below. Note that I wasn�t extremely precise, and even if I was, slight differences in processing will mean that these values can fluctuate for actual films. name ISO R G B nph 400 1.79 1.74 1.92 npz 800 1.48 1.54 1.72 reala 100 1.48 1.48 1.48 superia 100 1.3 1.19 1.12 superia 200 1.29 1.25 1.38 superia/press 400 1.53 1.43 1.38 superia/press 800 1.33 1.22 1.21 superia 1600 1.37 1.43 1.27 I hope this information is of use to you! If you find some inconsistencies or have improvements, please let me know. Greetings, Simon ---------------------------------------------------------------------------------------- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
