Photoshop - The Pen Tool

There is a variety of selection tools available within Photoshop, and they all have their area of application.

Perhaps the most difficult to use, and the most time consuming, is the pen tool, where you painstakingly draw an accurate boundary around the parts of the subject that you wish to work on.

I came upon the pen tool quite late in my PS career, but I regard it as being one of the most valuable selection methods, as it can accurately select to the nearest pixel.

You can use the pen tool in conjunction with say the Quick Selection tool, tidying up edges that have been missed, or ensuring that a straight line is indeed straight.

I normally work at either actual pixels view or one stage of  magnification above that when using the pen, in order to ensure an accurate selection.

There is a learning curve, but take heart, it's worth persevering. As with most things in PS, you can easily step back if you make a mistake.

Where do I use the pen tool?

It provides a nice clean boundary for a cutout (when you want your object surrounded by, normally, white space)

To preserve a section of an image when cloning, particularly if straight lines are involved. You pick the bit that you want to keep, and then select the inverse of your selection. Any cloning will then not impinge upon your important area.

To improve the accuracy in drawing a layer mask.

etc

26-7-16

Adjustment Layers in Photoshop

I use adjustment layers for most of my shots, I can't imagine being without them.

My workflow is as follows. I shoot in raw; title, keyword and adjust/develop in Lightroom; then transfer to Photoshop as a 16 bit TIFF for further work. The final image is stored as an 8 bit JPG. I don't normally keep TIFFs, which are very large files, but I do retain the original raw files.

What is an adjustment layer? My way of thinking about it, which may or may not be the whole story or even correct, is that an adjustment layer is analogous to placing a filter over the camera lens. The filter can change the contrast or colouration etc of the image, but can't change the basic content.

You can't therefore clone bits out of your image on an adjustment layer, you must return to the background layer for that purpose.

Adjustment layers are cleverer than filters however, as you can optionally mask off some of the filter effect so that it only affects a section of the image. Using a so called layer mask, you can choose the sections that you want the adjustment layer to influence. Further, you can return at any time to the mask to change it, using the brush and eraser tools to extend or reduce its active area (use the Channels window and select your active layer mask).

You don't have to have hard edges to your mask selection either, and most of my work is carried out using graduated masks, so that transitions don't stand out in the final version.

It can take a significant amount of time to construct a layer mask to suit your purposes, particularly if you are working at pixel level. Fortunately it is possible to re-select and re-use the mask, or, usefully, an inverse of the mask, later in the process. I recently learned that you can also copy a mask between layers.

The other great thing about adjustment layers is that, unlike a camera filter, they can be removed or made dormant at any time after the shot has been taken. So you can play with the image to your heart's content but then undo any wrong moves at a single key press. This means that you can experiment in a non destructive manner, always able to backtrack without changing the basic image.

You can use as many adjustment layers as you wish, but I rarely get beyond 5.

Why not do this in Lightroom? Well you can't, at least not with my knowledge/edition! True there are various graduated filter effects available, but with Photoshop you can accurately choose the exact area of an image that you wish to work on, working to the nearest pixel if need be.

Here's an example of how I have used two simple levels adjustment layers, sky and foreground, to enhance the appearance of an image. I hope that the differences are not too profound, in my view the best editing leaves a viewer believing that the image accurately represents the scene.

This is the image after developing in Lightroom

This one has had a few additional tweaks in Photoshop.

Ok, so how do you do it?

Easy, to obtain an adjustment layer select Layer, New Adjustment Layer, followed by the layer type that you want, e.g. Levels. At this stage you can give it a name.

It is useful to have the Layers window open in PS, when your new layer should appear above the background layer. There is a little eye symbol to the left of each layer and that determines its visibility, click to remove the eye and the layer is switched off. Another click and it is restored. Right click on the layer and you have the option to delete.

Layer Masks - again easy. Click on the background layer in your layer palette and then select a section of the image using any of the selection tools. You can optionally refine your selection, e.g. Select, Refine  Edge. Now open a new adjustment layer. Rather than covering the entire image its scope of influence will be restricted to your selection. 

How do you see the area affected? Open the Channels window and ensure that the little eye symbol is selected on the layer mask. The area of the image that is not affected will appear masked in red and your area of interest will not be masked.

How do you change the mask? Use the brush and eraser tools to extend or reduce it.

Simple.

If you do a lot or work on a layer mask, you might want to use it for another layer. No problem, you can copy a layer mask between layers.

Last edit 8-11-16

Perspective Correction Part 2

In an earlier epistle I listed a number of methods for shooting tall buildings and reducing or eliminating converging verticals. I listed the technique of stacking several images but noted that I had not tried this method.

Well I have now given it a go and have been reasonably impressed with the outcome, see for yourself below.

This is the Emerson Chambers building in Newcastle upon Tyne, situated at the head of Grey Street and currently occupied by Waterstones bookshop. 

I used a Sony NEX 6 camera fitted with the standard Sony 16-50 zoom lens at about 28mm focal length ( 42 mm equivalent full frame). The combined photo used 5 shots, starting at the base working upwards with a healthy overlap between them. 

The images were developed in Lightroom, with the only adjustment being a standard lens profile correction.

The developed images were transferred to Photoshop (CS4) as 16 bit TIFF files, and two different methods of combining them were tried.

1) The easiest way to do this is to use the File Automate Photomerge command, selecting all of the currently open images. This did a job. The main building was not too bad but there was some weird colouration in the sky while the buildings to the rear right were well distorted.

2) The next method is a tad more complex, but produced a better result.

I selected and copied all of the images over to the base layer (the bottom of the building) so as to obtain a layer stack of images. I then selected all of the layers and used the Layer Align command, followed by the Merge Layer command.

The resulting image was a great improvement on that produced by method 1, but there was still some distortion of the buildings to the rear right, and  a little chromatic aberration along a couple of edges. 

Some Photoshop skulduggery was able to sort all that out to produce a final photo that is 6616 x 4628 pixels in size. Printing at 300 dots per inch would result in  finished dimensions of about 22 x 15.5 ", but the quality of the original and, taking into account a sensible viewing distance, would allow a much larger reproduction were it required.

Edit - I've played around with this technique rather more now and have found that the degree of perspective correction appears to be related to the geometry of the base level shot. If your camera is completely level as you take the first shot, the software tries to mimic that geometry as it adds the layers above. While this may sound a good thing, an image without any trace of convergence of the verticals looks a tad strange, while the top layer has to be contorted rather more than might be considered comfortable in order to comply. I guess that I'm still in the experimental stage, but I am beginning to prefer a base level shot that is just off the horizontal, so that the resulting image has some degree of natural perspective after assembling all of the layers.

I've also tried the automatic panorama feature in Lightroom 6 (Right click, Photomerge), which is surely the quickest software fix for this problem, but I have not been as impressed with the results as with those that I have achieved using my venerable copy of Photoshop.

Last edit 25-2-2016