Professional Information Technology-Programming Book part 36 ppt

Just make sure you duplicate your image file, flatten it, and copy it to the original image file on its own layer.. You can use Photoshop CS2's new Lens Distortion filter to correct all

8.2.4.1 Lens correction

From a strict workflow standpoint, lens correction should be done at the same time

as other full-screen special effects Just make sure you duplicate your image file, flatten it, and copy it to the original image file on its own layer That way the

destructive processes that you're about to do will be on a separate layer If you have to redo this, just throw out the layer that contains your last attempt, then duplicate, flatten, and copy again

There are three facets to lens correction: perspective correction, pincushion, and barrel distortion You can use Photoshop CS2's new Lens Distortion filter to

correct all threeand more You can remove any chromatic fringing that you didn't get in Camera Raw or that you haven't been able to clean our of a JPEG image You can rid yourself of the vignetting that often occurs when you use very wide angle lensesa common practice in architectural photography You can also crop and resize your image to fit the original space Figure 8-28 shows an image that has all these problems and the result of fixing it with the Lens Correction filter

Figure 8-28 You have to look closely, but in addition to the obvious perspective distortion that resulted from tilting up with a 28mm equivalent lens, there is a slight amount of barrel distortion and vignetting in the original image

Here's how the corrections to Figure 8-29 were made:

1 After opening the image in Photoshop, and making other corrections, I

duplicated, flattened, and copied the duplicate image Then it was pasted into the original image, where it became a new layer, which is the target layer for this technique Be sure it remains the selected layer for the

remainder of this exercise

2 I chose Filter Distortion Lens Correction The result was the dialog you see in Figure 8-29 This dialog lets you combine a number of

corrections that, before Photoshop CS2, had to be made with separate

commands, interfaces, and even third-party filters

3 I removed the vignetting that is often caused by racking out a zoom lens to its widest angle As is often the case with this type of image, the vignetting wasn't all that noticeable But when removed, it makes a big improvement in the apparent quality of the image I dragged the Vignette Amount slider to the right until the corners brightened just enough Be very careful not to overdo it or you'll have a reverse vignette

4 The next easy correction is the barrel distortion that also happens when zoom lenses are zoomed out to wide angles How much of this distortion exists will depend on the focal length of the zoom, the size of your image sensor, the aperture used (wider is more), and the quality (which often

translates to cost) of the lens In this case, you had to look at the grid to really judge the distortion That's hard to do before you've corrected

Horizontal and Vertical perspective (camera tilt and swing), but you can do

it better on an image that hasn't already been distorted

5 This image needed no horizontal correction, but there was noticeable

keystoning of the vertical lines as a result of having to tilt the camera

upward to get the right perspective Once again, this adjustment is totally interactivejust drag the slider until you like what you see

6 This photo was shot on a tripod with a level, so there was no side-to-side tilt

If the photo you want to correct does have side-to-side camera tilt, correct it

by placing the cursor on the tip of the Angle dial and dragging until the image looks more or less level This dial is a bit oversensitive, so you have the option of typing an exact angle in the field to the immediate right of the Angle icon Also, you'll have more control if, after clicking inside the icon, you keep the button down and drag your cursor some distance from the icon before you start dragging from one side to the other You'll be able to make your adjustment with much higher resolution

Vanishing Point

Vanishing Point is a new tool in Photoshop CS2 that allows you to

magically clone in perspective so that, if you want, you can completely

repaper a wall or repeatedly copy a window to a whole row or column

(or both) of windows Although it's another one of those programs within

Photoshop, much like the Extract and Liquify Filters, Vanishing point is

amazingly quick and easy to use And, like those other filters, the way it

works implies that you should do it later in the workflow process Like

Liquify and Extract, this program is covered in depth in the "Vanishing

Point filter" section in Chapter 9

8.2.5 Still Life Retouching Tips

In this chapter, I'll discuss only a few things that you might want to do to enhance

the appearance of the objects in a still life I'm going to show you a few techniques you should consider at this stage by using a simple still life of some pottery

8.2.5.1 Adding water drops

Believe it or not, you can make water drops out of Photoshop even when you don't happen to have any glycerin around the studio Frankly, I recommend glycerin because it's cheaper and faster But I don't recommend putting glycerin on your computer So here's the deal: draw some water drops in different shapes with the Pen tool and then turn them into a selection by clicking the Make Selection icon at the bottom of the Paths palette Lift them to their own layer Make another layer and fill it with a radial white-to-gray gradient, then use the Layer Styles icon to turn the water drop into three dimensions, with a glow on the highlight side and a translucent shadow on the opposite side In Figure 8-30, you can see the water drop and the pen path, along with the Layer Styles palette and the settings used

Figure 8-30 The Layer Styles palette and a water drop made with it Be sure to use the same or similar settings as shown here

Make a variety of water drops in different sizes and shapes Make them about twice the size that you're ever likely to need them That way, you won't have to remake the set because you'll always have enough resolution Keep the water drops

in their own layered file so if you need them, you can just open the file alongside the target image and drag their layers to the target image If you're really wise, turn them into Smart Objects Then you can transform a single water drop in many different ways and do it completely nondestructively Of course, you could do the same thing with bugs, butterflies, flower petals, confetti, etc Many of those images are available as stock photos Figure 8-31 shows the same product shot, before and after being covered with water drops

Figure 8-31 A photo of a glass of water decorated with handmade water drops

The first water drop was placed by dragging the water drop layer shown in Figure 8-30 It was then transformed to the desired size and proportion and copied and placed a few times All the water drop layers were then merged and the Opacity of the merged layer adjusted to about 40 percent

8.2.5.2 Adding glow lighting

This technique is the same used in the "Re-lighting for emphasis" section earlier in

the chapter However, there's one more thing to add when it comes to still life images: put the glow inside a pen path made selection, just as I did on the model's shoulder earlier in this chapter The reason is that the objects in still life photos are generally much less "organic" than other types of subject matter The glow or shadow will look a bit unnatural if it also doesn't contain a geometric shape Also, the brightest part of the highlights in geometric forms are usually very obvious and geometric, so either use the Fill command when you're putting white or paint onto the Burn and Dodge layer

8.2.5.3 Adding lighting from behind translucent objects

This also follows the same technique as a glow, with some exceptions: if the

translucent objects have a textured shape, you'll have to make selections to match each of the texture shapes You'll have select any shapes that are inside the

translucent object if that object is something like a glass of iced tea Your best bet

is to backlight the object when the picture is taken Then you can add a bit of glow later if you like

Enhancements Later in the Workflow

Some of the things you're most likely to want to do to enhance still life

or product photos will be found much later in the workflow due to their

highly destructive nature Simplifying the background is something you

will likely do most frequently for still life photos One of the primary

reasons for shooting still life is to show a product and you won't want

anything distracting from it In fact, you usually don't want anything at

all around that product If you can't shoot it in a circumstance where you

can set up a tabletop studio, perhaps the best option would be to simply

knock it out

If you have to do that for an object such as a teddy bear, it is best to use

the Extract filter (see the "Using the Extract filter" section in Chapter 9)

However, most products are machine-made and have very smooth and

regular edges I find it much easier to knock them out by using a vector

path made with the Pen tool In fact, even when it's not perfectly

accurate, you can easily edit it by dragging the anchor points and

re-adjusting the curve handles Chapter 9 covers the use of the Pen tool

pretty extensively, as well as shadow casting if you have to emulate a

seamless edge or just want to make the product look like it's actually

sitting on something (see the "Lighting and Casting Shadows" section in

Chapter 9)

Most of the work done for "retouching" scenic images is covered

elsewhere in this book for workflow reasons (see the "Using Blend Modes on Regional Adjustment Layers" section in Chapter 7 and

"Where to Find the Pieces for Your Collage or Montage" in Chapter 9)

In those chapters, you'll learn to bring out detail, contrast, and to put skies and other elements into the image to "correct" the composition or

to add interest to an otherwise empty landscapeor sky The Vanishing Point filter, which can be very useful for doing things such as extending

a grassy meadow over a pile of garbage, is covered in the "Vanishing Point filter" section in Chapter 9 Also, you'll want to make generous use

of HDR images and the various techniques that can be employed to put them together You'll find a technique for making an HDR image from multiple RAW exposures in the "Increasing Dynamic Range by Making Multiple RAW Renditions" section in Chapter 4 You'll also find HDR covered thoroughly in Chapter 11