Pengikut

Khamis, 16 Julai 2009

Macamana Nak Guna Curves - How To Use Curves in Photoshop

Even if you’ve taken a good photo, chances are it can be improved or it needs to be adjusted to work in a collage or collection. Or even to just to intensify a mood. You can always make a good thing better – and curves is a one-stop-shop way to do that.
With curves you are able to:
  • Adjust the over-all contrast or tonal range
  • Adjust the local contrast or tonal range
  • Adjust the color
Let’s jump in and find out how. It’s simpler than it looks.

Overview

Image
Description
The idea behind Curves is all about re–mapping values. A pixel starts out at a certain brightness, and you change it to be brighter or darker.
The curves box opens as a straight line because you haven’t made any changes yet. That means that the brightness values before and after are the same. You will effect a change by changing the shape of the curve.
The points from left (bottom) to right (top) affect: blacks, shadows, midtones, highlights, and whites. By altering the position in these regions will affect the corresponding tonal range of your image. Leaving the line in the center will leave the tones unchanged.
You begin altering the brightness values by clicking once somewhere on the line. This will establish a “point”; this point can now be dragged to a different place within the grid, which causes that tonal value to change, either lighter or darker depending on whether you drag it up or down. The reason it’s a curve is so that the change blends smoothly throughout the image. An abrupt change in value can be very noticeable. The increasingly gradual change of the brightness values on either side of the change permit a very smooth and believable adjustment.
It’s important to note, however, that you can’t increase contrast in one region without decreasing it in another. The curves tool redistributes contrast. Therefore think of the image having a contrast allocation or budget and you need to decide how to best spend it.
Also, the curves tool will preserve the tonal hierarchy (unless you use uncommon negative slopes). That means that the brighter parts of the image will stay brighter even after your conversion – just maybe not by the same amount.

Quick Tip

Keep effects on adjustment or separate layers to enable quick alteration or removal at any time during the color correction process. (Layer > New Adjustment Layer > Curves. Or at the bottom of the Layers panel.)

S- and Inverted S-Curves

 

Rollover Image
The S-Curve and the Inverted S-Curve are two curves most commonly used. The S-Curve adds contrast to the midtones while subtracting from the shadows and highlights. The Inverted S-Curve does the opposite.
Often in photography, it’s difficult to expose your image perfectly. Brightness or darkness in tonal ranges can benefit from optimization. The S-Curve is often useful in these cases – not to mention, quick and simple.

Empty Tonal Range and Histograms

 

Rollover Image
One very useful and important function of curves is to correct empty tonal ranges – in the histogram edges (blacks and whites) or gaps in between (shadows, midtones, and highlights). An under exposed image can be helped by pulling in the black and white points to correct the exposure.
Or if there are gaps in between the tonal peaks you can decrease contrast in specific parts of your image – thereby freeing up the contrast to be used in the more visible areas of your image.

Clipped Highlights

 

Rollover Image
Images containing a bright light source, such as the sun, can often be harsh or posterized (also called color banding). Posterization of an image entails conversion of a continuous gradation of tone to several regions of fewer tones, with abrupt changes from one tone to another. This can create an unrealistic look, and often a smoother transition to white is preferred.

Correcting Color Balance

All curves thus far have been applied to RGB values of luminosity. But they can also be used on individual color channels to correct color casts in specific tonal regions. Often the color in an image is correctly balanced, but due to reflection or a light source with a varying temperature or color, you may see unwanted tints in a tonal region. Changing the white balance or adjusting the overall color would inadvertently harm the other tones. So we can selectively increase or decrease the amount of a color cast in the red, green, and blue channels to achieve perfect balance.


Image Description

Any adjustments upward of the diagonal line in the red channel increase the red in the image. Lowering, below the diagonal line, increases the cyan. The other channels are the same: Upward in the green channel, green; lower, magenta. Upward in the blue channel, blue; lower yellow.

Image Description
RGB color images should be thought of as being comprised of a composite channel and three grayscale channels containing the values of the three colors – red, green and blue. This is shown in the example above of the red on the left, green in the middle, and blue on the right.

Window > Channels to see this on your image.

 

Rollover Image
You can see in the image above that there is a slight blueish cast in the color tone. Not to mention, the image is slightly washed out (improperly exposed).
As you can see, the sky is already quite white, so we won’t want to effect the highlights and above. By lowering the curve in the midtones and shadows, without effecting the highlights, we solve the exposure problem. Then we’ll get rid of the blue color cast: By lowering the blue in the low end, we eliminate the problem and the gowns go to black – as they should be.

Note

If precise color adjustments aren’t required, simple color balance correction might be easier (Image > Adjustments > Color Balance).

Blending Modes

Image Description
Also, curves adjustment layers (Layer>New Adjustment Layer> Curves) can be set to make curves only apply to a channel – such as Color and/or Luminosity – which allows for further, varied control. Another benefit is that it can make your adjustments more subtle through use of the opacity controls for the layer.

Notes

Practice makes perfect. The more you use the tools and techniques available to you the better you’ll get, improve your photography, and have fun.
Here are some things to remember when using the curves tool:
  • Minimize use of the curves tool, as anything which stretches the image histogram increases the possibility posterization.
  • Avoid the use of the curves tool on an already altered image.
  • Perform curves on 16-bit images when possible. (Image > Mode > 16 Bits/Channel)
  • For extreme levels of color correction, consider applying curves using LAB mode
READ MORE- Macamana Nak Guna Curves - How To Use Curves in Photoshop

Tiger Skin Web Design Tutorial - Photoshop Tutorial

This tutorial demonstrates how to make a website with a realistic tiger skin texture.
pen up Photoshop, make a new image, and follow along with this tutorial.




1 – Creating some diamonds

Make a new layer.
Select a rectangular area, as shown in diagram [a].
Fill the area with black.
Press Ctrl+T to Transform the selection. Move the cursor near the bottom right of your rectangle, so it turns into a curved arrow. This arrow allows you to rotate the object. Rotate your rectangle slightly, as shown in diagram [b].
While holding Ctrl and Alt, drag the rightmost point upwards, until the shape resembles a diamond (no need to be exact), as in diagram [c]. (Holding Ctrl allows you to move one corner by itself, and Alt mirrors your actions, which moves the leftmost point downwards in this case.)
Press Enter to confirm the changes.




2 – Replicating the diamonds

With the Move Tool selected, hold down Alt, and drag your diamond somewhere else. This makes a copy of the diamond. Make about five copies of the diamond this way.
Once you've made your copies, press Ctrl+T to transform the current diamond. Drag its corner a bit, to make it different in some way.
Hold Alt and use the Move Tool to make copies of your new diamond. Arrange all your diamonds in an irregular line, as shown. Vary the position of the diamonds a bit, but try to keep the bottoms of the diamonds all at around the same height.




3 – Turning the diamonds into tiger stripes

Merge all your diamonds onto one layer. Do this by clicking on a layer in the layers list and pressing Ctrl+E to merge it with the layer below it. (Don't merge anything into the Background layer.)
Press Ctrl+T to transform the diamonds. You may need to Zoom out (Ctrl -) at this point.
Elongate the selection, by dragging the bottom down and the top up. Drag the whole selection upwards, so you can only see the bottoms of the diamonds, as shown in the diagram. Grab the corner and rotate the stripes slightly.
If you're not happy with your stripes, click on the History tab, undo some steps, move your diamonds around, and try again.




4 – Adding a Wave to the stripes

Click Filter, Distort, Wave. Set the Number of Generators to 1, the Wavelength to 120 (both sliders), and the Amplitude to 15 (both sliders).
Click "Randomize" a couple of times, until you get some nice curves.
Click OK.




5 – Setting up a colour Gradient

Select the Gradient Tool. In Photoshop 5.5, this is a tool on its own. In Photoshop 6.0 and 7.0, you'll need to hold down on the Paint Bucket Tool to see it.
Click on the visual representation of the Gradient at the top left of the screen. (If you're not using Photoshop 6.0 or 7.0, you'll need to click on the Options tab, and click "Edit" instead.)
Set up brown, orange, and white tabs as shown.




6 – Creating the tiger's fur

Click on your Background layer, then click and hold down the Gradient Tool at the top of your image. Move the cursor downwards, and then release the mouse button.
To give the fur a realistic texture, click Filter > Noise > Add Noise. Put in 5% worth of Monochromatic, Gaussian noise.
Click Filter > Blur > Motion Blur. Set the Distance to 5, and choose a diagonal angle.
To give the image a smooth transition from fur to blank white area, use the Brush Tool, with a soft brush about 45 pixels in size. Brush across the bottom of the image. Hold Shift while you do this, to keep the line straight.




7 – A shadowy text header

Use the Text Tool to Type in your heading in black. I've used Palatino Linotype font here. Make the first letter bigger, and increase the letter spacing by putting a space between each letter (you can increase the Tracking instead, if you have the option.)
Right-click on this new text layer, and Duplicate it. Change the font colour to white.
Choose the Move Tool, and press Up Arrow, Left Arrow. This moves the white text, so that only a small part of the black text is visible, which makes it look like a shadow.
You could use Blending Options to do this instead, but this method is easier, and can be done in any version of Photoshop.
Click File > Save For Web, and save your image as a Quality 60 Jpeg.




8 – Recycling the header to make a footer

Click the eyeball next to each of your text layers to hide them.
Click Image > Rotate Canvas > 180°
With the Move tool selected, move the black stripy layer down, so only the tips of the stripes are visible.
Click on the "fur" layer, and Press Ctrl+T. Drag the top of the selection down, to make it narrower.
Use the Selection Tool to select the area you want, and click Image > Crop. This trims off the unwanted white space at the top.
Click File > Save For Web, and save your image as a Quality 60 Jpeg.



 

Tigerskin Photoshop Training We are experts in the field of graphic design training. We specialise in Adobe Photoshop, and run regular Photoshop tutorial classes.

Student Portfolios Feel free to browse the web design and graphic design portfolios of our students.

Legal Disclaimer We're not real tigers. We can't be held liable for any biting or clawing incidents that may occur.

9 – The finished product

In your web editor, insert the images. I'd recommend using the font colours and styles I've used in this diagram. I'd also recommend that you make up your own text. :)
READ MORE- Tiger Skin Web Design Tutorial - Photoshop Tutorial
Related Posts with Thumbnails