Photoshop For Beginners - Understanding Levels and Curves Input Values

When you set the INPUT value in the Levels or Curves dialog either by dragging the black or white triangular sliders or typing a value directly into the Input box, you are telling Photoshop to change all of the pixels in the image that have this new tone value so that they match the default OUTPUT value. For example, when you move the white slider in the Curves dialog to 250, you are basically saying "I want all the pixels with the value 250 AND HIGHER (i.e. the range 250 to 255) to have the same value as shown in the OUTPUT box."

Since the default OUTPUT value is 255 for white, all of the pixels in the image with a value of 250 or higher will be made to be pure white (value 255). The other light tones in the image will also become lighter. The same is true for the black slider. When you move the black slider you set the INPUT value which will change all of the pixels with this value AND LOWER equal to the default OUTPUT value which is 0 (i.e. black). For example, if you move the black slider or set the black INPUT value to 25, all of the pixels with a value of 25 or lower will be made equal to the output value of 0 (black). This will also cause all of the shadow tones also to darken.

You are actually setting the upper and lower limit values of the white and black tones in the image which in this example would increase the overall contrast of the image. So, if you have a low contrast image that hasn't got a black tone and hasn't got a white tone, you would normally be saying "OK, the darkest tone in this image has, say, a value of 20 BUT this is not true black and I want it to be black. Right, so I need to set the INPUT value of the black slider to 20 and leave the OUTPUT value at 0."

This will change the value of the selected tone from 20 to 0 thus increasing the depth of the shadow tones. Note that all the tones in the dark areas will be lowered in value proportionally. You now have either a Levels or Curves tone adjustment that has 'mapped' the value of 20 down to 0. Working with the lighter tones now, let's say the lightest tone in this same image has a value of 230 (a light grey tone, typical of low contrast photos). Now let's assume we want the image to have a pure white. So, we need to change the value of this tone from 230 so that it looks white (value 255). Using the Levels or Curves adjustment dialog we move the white slider until the INPUT value is 230 and leave the OUTPUT value at the default of 255. This will change all the tones with a value of 230 so they have the new value of 0 (zero) which will change them to become white in the image.

The result of these two changes to the black and white input values will be that you have increased the image contrast to make it fill the full tonal range and appear more 'normal'. Now you understand how the Input values in the Levels and Curves dialogs work and how to use them to correct a low contrast photograph.

Photoshop Tutorial - How to get Great Skintones with your Digital Photography

Good skintones. The search for the holy grail of digital photography. I have been banging our heads against the wall for years trying to perfect "THE ONE SIZE FITS ALL" solution to working with skintones and I'm talking about capturing, workflow, output, the whole nine yards. What I've figured out so far is that skintones are somewhat subjective. The procedures that ultimately create good skintones are as follows:

Good capture:

When you capture the image 99% of your job is done. If your exposures are off and your colorbalance is off, then your skintones will be off. Of course this means your lightmeter will be your best friend (second to your dog). Be on top of your exposures like dirt on a pig. Know your histograms and image tones. Don't just use your LCD as a reference. Your LCD brightness varies, and is not 100% reliable to use on it's own, however it is an integral tool that works with everything else. Never get lazy here, always check your exposure, know your exposures and keep it
accurate. Make this a part of your mind set and workflow. And don't forget to test new stuff, never assume....

Colorbalance:

I like to shoot a greycard under the lighting conditions we are shooting in as a custom whitebalance setting. For some reason a greycard seems to work better for us than a whitecard. What can I say. I get images that are neutral, I can warm them up later if I choose. However, for many digital photographers, using a white card to create their custom white balance weems to work just fine.

Workflow:

I like to get an idea of what a good skintone is by using the colorpicker. Now remember, skintones are subjective, so it's purely arbitrary but you will get used to it in time. So, as a rule of thumb, using the color picker, depending on the actual pigmentation of the subject we find the reds are about 20% higher than the green and about 30 - 40% higher than the blue. Since during the capture the tone has been turned off (in camera parameters), I can add more to the skintone by using colorbalance and saturation.

Assuming that you have good capture, (exposure/whitebalance), there are several ways to acquire or enhance skintones. One of the best ways is by using the selective color (IMAGE/ADJUSTMENTS/SELECTIVE COLOR, or ALT-I-A-S). I have been using this for a little while now, and so far it's rendered me outstanding skintones. Here's how it works.

Simply reduce the amount of cyan in the reds. Usually about 40-50%. I could go more, but I hold off. Why? Because when I adjust the contrast later it will bring out more tones in the image, thus giving me more red in the skin. There is al lot or red in the skin, especially caucasians, so by doing this technique you will give most people more warmth and glow to their skin tone- but be careful!! Do not over do it.

The thing I like about using the selective color this way, is that I am only working with the red tones. If I didn't want to affect any other reds (like the reds in her coat) I can simply do several things:

1. make a selection around her face and then perform the adjustments.

OR

2. after the adjustments simply use the history brush and erase the areas I don't wish affected.

That's it. Simple isn't it, when you get down to the basics.

Photoshop For Beginners - The 3 Basics of Using the Curves

Most beginners to Photoshop (and many advanced users) avoid using the Curves command because it reminds them of school math classes and geometry! I know how you feel, but if you take a little time to understand the basics of how curves work you will lose your fear - trust me. In this article I will show you the 3 basics you need to understand to effectively use Curves.

What do Curves actually do?

The Curves are very like the Levels in that they are used to adjust the tonal contrast of the photograph. More importantly they are also used to adjust the look of the various grey tones of an image. The difference between Curves and Levels is that the Curves dialog allows you to control any portion of the grey tones whereas the Levels changes all of the various tones at the same time; you have less control with Levels than you do with Curves. This is why professionals prefer using Curves; they put you in control!

Use the Curves command to change overall contrast by:

1. Choosing the first tone in the image you want to have a pure black value.

Known as black point adjustment, moving the black slider along the bottom of the grid in the Curves dialog allows you to set which tone will be pure black in the photo. Bear in mind that if you move the slider past the start of the graph shape you will lose some of the subtle really dark tones and this will lose details. For example, if you move the slider to the right so it is at the very left end of the graph (the value of the tone at this point will be shown in the Input box), this value will be changed to pure black (value 0) and all the other grey tones will be darkened proportionally. If you move the slider even further to the right i.e. make a slightly higher tone value pure black, you will lose any tones shown in the graph that are to the left of the slider. Let's say the very end of the graph shows an Input value of 20, this is the darkest tone in the image and so when it becomes pure black we do not lose any other tone values because the other tones have higher values (they are lighter in tone). However, if we move the slider further into the graph, say to Input value 30, we will lose all of the tones between 20 and 30 because they will all be made to be pure black.

Now we know how to set the darkest tone of the image to pure black to obtain rich looking shadows.

2. Setting the pure white tone of the image.

Now we use white point adjustment to set the lightest tones of the image. Moving the white slider to the left so that it just touches the right end of the graph will make the tone at that position become pure white. Just as with the black point adjustment described above, since all the other tones below this point are lower in value (i.e. they are all darker), we do not lose any of the subtle light tones. However, if we move the white slider further to the left so that it is inside the graph shape, we will lose all the tones to the right of the slider as they will be made pure white in the image.

Setting the end points in the Curves dialog as explained above is exactly the same as setting them using the Levels dialog. For the end points the two commands do exactly the same job. The real power of Curves is in how we can control the other tones of the image as we shall now see.

3. Controlling the intermediate tones of the image.

The first difference you notice between Levels and Curves is that there is no grey slider shown in the Curves dialog and that there is a diagonal line from one corner to the other that cuts across the histogram shown behind this line. (To understand more about the graph in the Curves dialog see my article on understanding the histogram.) This line is actually a curve without any bends in it! When the line is straight (as it will be when you have only set the end points in 1 and 2 above), the relationship between the intermediate tones is being affected equally by the line. However, you can now click and drag anywhere on this line to create a curved line. When the line becomes a curve shape it no longer controls the tones equally. The real power of the Curves adjustment is that you can click and drag from several points on the line to create any curve shape you want. By changing the shape of the line into a curve you can control which portions of the tone scale are adjusted. You can also simply click on the line to create fixed points that act as anchors to stop the line from curving. When the line remains straight no changes occur to the tones in that area. This is how you can select just a portion of the tones to alter; create several anchor points along the line over the tones to preserve and then bend the line up or down in the area you do want to change.

A word of caution; if you have the curved part of the line that covers the shadows of the graph higher that the curve over the lighter tones you will cause the tones to reverse. This is known as posterisation and is not good! Try to make sure the curve is raising all of the way from left to right and that it doesn't dip down too much in the middle section.

There you have the 3 basics of using the Curves command. Using Curves is the most powerful way to control the contrast of your photograph and you should now be able to use it with confidence.

Photoshop For Beginners - How Much Should I Sharpen a Photo For the Internet?

What is USM or Unsharp Masking?

The most common method of sharpening an image in Photoshop is to use the USM or Unsharp Mask filter. The unsharp mask filter has its roots in traditional darkroom printing and involves increasing the contrast at the edges of detail. This increase in contrast produces a perceived increase in sharpness.

How much USM should I use?

Before we get too far let's just establish that there isn't a 'one stop' group of settings for all occasions. Many beginners think you can use just one amount of USM for all images but that is not usually possible. The amount of sharpening has to be done on an image by image basis.

Of course, if you regularly produce images of the same basic size, for example for your internet gallery, you may find that one amount of sharpness works most of the time; for that size of image! To determine the amount of USM required, it is best to look at how we want to use the image.

The Internet

For the internet, where the image is to be displayed only on screen, we usually resize the image so that it produces a reasonable size on the computer monitor. For screen display the 'resolution' of the image shown in the Photoshop image size dialog is irrelevant (this is only used for printing); the only important information is the actual pixel dimensions of the image. Now most monitors display at a screen resolution of 96ppi (pixels per inch) and the commonest screen pixel sizes are 1024x768 or above. So, if you want an image to fill half the screen on a 1024x768 display the width needs to be 612 pixels. This would produce an image of just over six inches wide on the screen.

So, we resize our finished image (and save it as a copy!) to 612 pixels wide. Now we apply USM. Since this image is only destined to be viewed on a computer screen you can simply use your eyes to determine how much to sharpen. Adjust the USM settings visually with the preview box checked. If you get haloes around edges bring it back, you have gone too far!

This is easy as you can see the result instantly, just use your judgement. If your screen size is bigger than 1024x768 adjust the figures for your own screen since you have absolutely no control over other people's screens. Just keep thinking about how big you want the image to appear ON SCREEN and use pixel sizes to get there (or use 96ppi to calculate screen inches). This is all done for you in PS using the Image Size dialog so you don't need the math.

If you are submitting your photos to online libraries or for use on printed products you should follow the guidelines set down by the particular website you are sending the images to. Most commercial websites will have very detailed help to guide you.

By doing some simple tests you should learn all you need to know about USM for Internet photos without worrying about how much or little to use. By the way, this is also getting to know your visual preferences for your Internet based photos!

Photoshop Photo Effects - Photo Edge Burn Effect

What is Edge Burning?

In traditional darkroom printing, especially in black and white, the enlarger systems used often suffered from 'fall off' (the light in the centre of an image was brighter than at the edges hence the centre of the print always had a lighter area around it.) The same is true of cameras; the camera image is brighter in the centre than at the edges. This is most evident with really wide-angle lenses but is present to some extent for all lenses.

This is commonly called 'fall off' and if you want to get really technical it can be calculated using the Cos4θ rule of trigonometry but I digress. As a rule of thumb, most lenses lose about 1/3 to 1/2 a stop of light at the edges of the image compared to the centre.

So, to compensate for negatives and enlarger problems of fall off, most expert printers use edge burning to balance the tonal difference between the centre and edge of the print. Edge burning is simply adding more tone to the edges of the image. In printing it was usual to add about 10% additional exposure time for each of the edges.

Edge Burn and Composition

Now, edge burning has another important effect and that is to do with visual perception and not deficiencies in photography. When you darken the edges of an image it holds the viewers attention into the picture and prevents the eye straying beyond the boundaries of the print or image. This is a subtle technique for concentrating attention inside the image borders.

Inner Glow to Edge Burn in one easy lesson.

One day it dawned on me that the 'inner glow' layer effect in Photoshop produces an 'edge lightening' around the four sides of an image and although this is the exact opposite of the desired edge burn, it got my brain cells sparking so I dove into the Inner Glow dialog to see what gives.

My easy Photoshop edge burn effect just needs you to change the settings for the Color, the Blend mode, and usually the Size values in the Inner Glow dialog and there you have an edge burn. Change the colour to black, the Blend Mode to Multiply, and the Size value for the width of edge burn you want.

The Opacity value can be modified down to around 5-15% depending on how obvious or subtle you want the effect to be. Sometimes I use higher values to make the edge burn very obvious and then it becomes part of the image composition and mood.

You can only apply the layer effect to a real layer (not the background so convert it to a layer) and sometimes you will need to add a new layer filled with white and blend mode set to 'Multiply' at the top of the stack to add the effect to for the best results.

There you have a very easy and controllable method of quickly adding edge burn to an image. Please note, although there is a Photoshop layer effect called 'Inner Shadow' which you may think does the edge burning job; it doesn't! This is because the Inner Shadow effect only applies the effect to two sides of the image to create a shadow and not an edge burn on all four sides.

Retouch/Digital makeup in photoshop

Digital makeup in photoshop.This was just a pic i tok of a model without any makeup.Just to see how much i cud do with it i photoshop. Music Weh www.weh.erikevju.com



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