> Thanks William, > > At the risk of sounding far too tedious, can you explain "Channel > operations" as it sounds like something out of WW2!!!
Actually, WW3 - but we won't go there - not yet anyway. Channel operations, otherwise known as CHOPS is when you use RGB/CMYK/Lab channel information as selection masks. It is also very difficult to explain. <G> OK, you have scanned your dense neg three times to give a highlight, a midtone, and a shadow rendition of what was in the negative. Stack them up in a layered PS document, and use 'Difference' to accurately align one above the other. If you have scanned in greyscale, then the information in each R-G-B channel is the same. So.....duplicate the Red channel from each layer as an extra Alpha channel. Make sure you label everything. I mean everything, otherwise you will get lost. Now, this is where the fun starts, because you are going to have to experiment. Select a layer (say the shadow layer) to make it active, and load up a Red Alpha channel from (say) the highlight layer - and press Command-J to turn the selection into a new layer. Then position it above the midtone layer. This may or may not give you (a) result you (might) want, but in principal any channel information can modulate any aspect of a picture file. The trick is to experiment on different layers with different Alpha channels until you find what YOU are looking for. As each picture is different, then no two CHOPS are the same. As there are ten discreet channels of information in every picture file, it means that there are ten to the power of ten variations as to how CHOPS can be applied. You can even use inverted selections, or apply selections to Alpha channels themselves! The choice is truly infinite. Kinda spiritual, but as this is a technical kinda forum we won't go there either. The big thing is that unlike using Curves, CHOPS is non pixel destructive. You can mash around until your heart's content, and you won't get posterisation creeping in. If you do get lost, then set the History setting to about 100 beforehand. In this way you can track backwards and forwards to hit the spot where your short term memory lets you down:) Very very useful. CHOPS is also brilliant for use with Action scripting. There is no point in me blinding you with science, as CHOPS has immense power, it is poorly documented, there is only one book on it, and even the authors (who are seriously sussed!) will admit they don't know everything. If my memory serves correctly, Jeff Schewe is THE top bod to explain CHOPS. best William Curwen www.william.ws =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
