Igor, simply put: curves _cannot_ do what you want to do. In image processing terms, curves is a simple one-to-one pixel mapping function. One level in, a mapped (lookup table) out.
What you want to do (edge detect) involves nearby neighbor pixels, so it's a many-to-one function. Convolution is one technique that does this, and Photoshop provides you a direct way to specify a custom kernel (up to 5x5, see Filters- > Other -> Custom). You can also do this in free packages such as Imagemagick. Export your image to TIFF, process it externally and reimport it. Here's some reading: https://en.wikipedia.org/wiki/Kernel_(image_processing) On Sat, Sep 3, 2016 at 2:57 PM, Igor PDML-StR <[email protected]> wrote: > > > How can convert a photo in LR to get only the edges of all objects? > > I've asked this question about 2.5 years ago here, and Bruce and Jostein > have offered a couple of ways to do that in PS. > I 've been trying to achieve this effect in LR by playing with the tone > curve, but I cannot so far. > > In essence, I am trying to get this type of image where only edges are > visible: > http://42graphy.komkon.org/swing/ch-2008/1-selected/IMGP4530_1.html > > I've got close to that by essentially bringing the entire curve down, with > only a spike in the mid-range. That highlights some edges, but > (1) not all of them and (2) it highlights some non-edge areas. > > I am starting to think it might not be possible in LR... > Any ideas? > > > Igor > > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions. -- -bmw -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
