Sunday, June 13, 2004

Photoshop hints can save some screams

Many people have Adobe Photoshop for work or play but don't know how to use it for a quick color correction and prepress. Consequently, they take whatever the scanner hands them (typically a flat, lifeless version of reality).

Although there are many adjustments possible, here's a fast set of basic controls to make bland images pop. These are the immediate actions I use when I'm on deadline and have little time to deal with prepressing the image. This could save someone 10 years of deadline stress along with the associated screaming and cursing at a computer screen. It works on digital camera images as well as images scanned from negatives.

I tend to use numbers instead of eyeballing images because it saves time (especially on slow computers with low RAM) and increases my confidence about the final result without looking much at the actual image, which is different on every non-calibrated monitor.

If you know what you're doing, here's the speed readers version:

Open. Ctrl 0. Crop. Ctrl M. Auto correct. Save As. Ctrl M, set black point, white point, gray point on black. Ctrl L, set input levels at 10 | 1 | 240. Save. Select highlights. Feather. Invert. Try contrast at 6 (adjust to taste). Select shadows. Feather. Ctrl L, try 3 | 1 | 245. Save.

This version should be small enough to print and tape to a monitor.

Here's the very long version:

Open Photoshop.
Choose and Open an image file.
Simultaneously press Ctrl and the number 0 to fit the image to the screen.
Crop the image to the best composition and size.

Simultaneously press Ctrl and M. Or, choose from "Image" the menu bar, then "Adjustments," then "Curves" to get the same subscreen.

Move the mouse cursor over "auto" and click. Sometimes this is good enough for most people. However, it occasionally really messes things up. If it does, choose "cancel" and perform the following steps without the initial automatic adjustment. If the auto adjustment is fine, choose "OK" and move to the next step.

Save (Save As) the image onto your hard drive/desktop (particularly if the computer doesn't have a lot of RAM).

Simultaneously press Ctrl and M. Or, choose "Image" from the menu bar, then "Adjustments," then "Curves" to get the same subscreen. This time, we're going to set the image's black, white and gray points. As your skill improves, use the magnifying glass to enlarge areas for the most precise pixel selections for the following.

Set your mouse cursor directly over the center of the diagonal line on the curve. Press and hold the mouse as you drag it toward the lower right corner. The image should appear to fade and become brighter. If it becomes darker then your controls are set opposite, so move the cursor to the opposite corner. Release the mouse when the darkest parts of the image are barely visible. The darkest of these points is your black point.

Move the mouse cursor over the black eyedropper on the right side of the "Curves" dialog box. Click. Now move the cursor, which should be shaped like the eyedropper (hit the Caps Lock key if you want more precision), over the darkest point of the image and click. The image should look basically like it did before, but slightly darker and with a little more umph to it.

White point is tricky because you must choose the white point without the help of moving the entire curve. Select a pixel which is most likely pure white and set the white point with the white eyedropper. The color probably shifts to something horrible, it's fine, we're about to fix the gray point.

Gray point is often the most difficult to set because it's subtle. By definition, gray is a color with a neutral hue between white and black. The best way to set the gray point is to remember the exact position of the original black point and use it as the gray point. Since black is also gray, it color balances if the original black point is used as the gray point as well. If the color seems to still be off, try setting the gray point in a shadow area of a known white, black or gray area. Be careful about over adjusting gray if you aren't certain about the calibration of the monitor you are using.

If you like it, choose "OK." If not, choose "Cancel" and try again until you're satisfied.

Next, simultaneously press Ctrl and L. Or, choose "Image" from the menu bar, then "Adjustments," then "Levels" to get the subscreen. Manually set the input level numbers at the following 10 | 1 | 240. This takes some of the flatness out of the image by compressing the image range. It makes light areas brighter and add some depth to the dark areas while adding an overall contrast. If you like it, choose "OK." If not, choose "Cancel."

Save the image.

Next, we're going to hold the detail in the highlights while recovering some detail to the darker areas of the image. There are two ways to accomplish this. I'll explain both. When I have time, I use a combination of both to balance the image for maximum detail.

Move the mouse over the tool bar. Select the magic wand tool. On a PC machine, look at the top of the screen for the word "tolerance." It should be at 36. If not, hit "Enter" on the keyboard and change the number to 36.

On Mac machines, hit "Enter" on your keyboard. A subscreen appears with the settings for this tool. Set the tolerance at 36.

With a good setting, move the mouse over an image highlight. Click the mouse. You'll notice a shimmering line appear around the highlight area. If it's in the wrong area, hit Ctrl Z or "Edit" then "Undo Magic Wand." Try again.

To select additional highlight areas, hold down the shift button while moving the mouse over those areas. Each additional selection can be undone. If it's all wrong, click anywhere outside the selected image and it all disappears.

A faster way to do this is to select a highlight area. Then choose "Select" from the menu and "Similar." This can be done several times as needed.

I also like to choose "Select," then "Grow" to expand the range for pixel variations. This could occasionally cause some strange selections, so be careful before the next "Similar" after a "Grow" command.

Once the highlights are selected to your satisfaction, we need to make the following adjustments blend gracefully. Simultaneously hit Ctrl, Alt and D for a Feather Selection dialog box. Or, from the menu bar, choose "Select," then "Feather." Set the feather radius to 15 pixels for most standard images. Use a smaller number if the image is much smaller. The point is to smooth out the selection lines.

Once the selection is feathered, choose "Select" then "Inverse," or simultaneously hit Ctrl Shift and I on the keyboard.

I prefer to hide the selection lines to see the results more accurately. To hide the selection, simultaneously hold down the Ctrl and H keys.

Next, choose "Image" then "Adjustments" then "Brightness/Contrast." A dialog box will open. Hit "Tab" or mouse over the "Contrast" numerical box. Set it to 6. This can also be done by sliding the scale, but it's not as fast. Hit "OK" and be prepared to undo (Ctrl Z) the change.

Look carefully at the image and hit undo (Ctrl Z) a few times to see if you like the difference. If not, hit Ctrl Z and try a lower number. If it still isn't enough contrast (this also changes the color balance) repeat the steps above with a maximum of 6 rather than bumping up the contrast number.

By now, the image should be fairly close to looking good. If the shadows are looking a little flat or are still too dark, we have one more round of adjustments. Select the shadow areas as was done with the highlights, but don't invert the selection. Feather the selection as previously done.

Next, simultaneously press Ctrl and L. Or, choose from "Image" the menu bar, then "Adjustments," then "Levels" to get the subscreen. Manually set the input level numbers at the following 3 | 1 | 245. The dark areas can be made darker by increasing the first input number. The shadow areas can get more highlight detail (rough concept) by decreasing the top input number (to 240 for example). If you like the changes, choose "OK." If not, choose "Cancel."

Write a cutline and get to the next image because the press rolls in five minutes with a big freaking blank spot if you don't HURRY.

I still suggest the original steps (above) for images where time isn't an issue and quality is important. The steps are accurate and largely predictable and tend to produce consistently professional work.

It's also best for new PJs. The following steps are designed for PJs who've been at this a while (and can manually fix problems) and own a newer version of Photoshop.

The Photoshop program has evolved since my first post, so I'll address useful new features. With CS2 and CS3, there are some amazingly fast options for deadline PJs trying to crank out images fast or a high volume of images (for slideshows or freelance "event" photos).

These options won't work on all images. Again, if any step doesn't look correct, back up in History and work the image the "old fashioned" way from the point it strays.

CS-2&3 adjustments:
Open a generic .jpg file and crop to taste. Create the following Actions to maximize process speed:
1. Auto Color (Shft+Ctrl+B)
2. Set Shadow/Highlights (the Ansel Adams button)
      Shadow = 1
      Highlights = 4
3. Set Brightness / Contrast (for deeper blacks)
      Brightness = -1
      Contrast = 4
4. Set Unsharp Mask (as final step once image is fully toned)
      Amount = 110%
      Radius = 0.5 pixels
      Threshold = 0
If you're really lucky, the generic image should look good. Add 3 | 0 | 255 to the Input Channel in Levels, and you should be done. Save As (rename), put the Actions back into Button mode and move to the next image.

For extra speed, combine all the actions above under a single button and lable it "Feeling Lucky." If you're truly lucky, the one button will do it all. If not, back up through the History to find the problem and manually continue from there.

I'd also suggest creating a Similar, Grow, Feather button to fine tune the highlights and shadows to taste.

The five action buttons should be able to handle most images. They can be combined into a batch command (or the "Feeling Lucky" button) with a catch folder to handle most high-volume assignments efficiently.

In these circumstances, Copy selected images into an additional folder to protect the originals before starting the batch command. Go through the output folder and check for incorrectly-toned images. Redo those images manually the original way.

Enough for now,

1 comment:

merkaz said...

thanks for the blog….its really nice & useful information