Auto-levels

mercphoto

I have a question about using auto-levels in Photoshop CS. I'm looking for quick ways to make moderate improvements to my racing images. Due to the number of images and the hurried rush to post to the web, I shoot large-fine JPG with Parameters 1 on my Canon 20D. And since this is an outdoor sport in the sun, the camera never gives me problems with white balance or exposure. But it appears that auto-levels can be an effective means of improving contrast.

Is auto-levels a good idea for my needs? Any tips on when to use, or not use it? And any issues with doing this on an in-camera JPG? Thanks!

cletus

I'm going to try and answer these in reverse order:

mercphoto wrote:

And any issues with doing this on an in-camera JPG?

I can't think of any. Shouldn't make any difference what format you shot in the camera.

mercphoto wrote:

Any tips on when to use, or not use it?

Auto Levels should help images with low contrast. It can also correct color casts. It can help brighten dark images, or darken bright images. The thing to keep in mind is that Auto Levels will work fine as long as it is making minor corrections. If the corrections start to get more dramatic, you would be much better off making them manually. Another time you don't want to use Auto Levels is if there is a color cast that you want to keep. Sunrise/Sunset for example. Usually you want to keep the warm light from sunrise/sunset. Auto Levels will tend to strip the color cast and give you plain balanced light.

If you've got a bunch of shots taken under the same lighting with similar exposures, you might try making a manual levels or curves adjustment to one of the images and then apply the same adjustment to all of the images. Then see if you like the manual adjustment version or the Auto Levels version.

wxwax

All I can say is that after getting some weird results using Auto Levels, I stopped using it and adjusted everything manually.

mercphoto

wxwax wrote:

All I can say is that after getting some weird results using Auto Levels, I stopped using it and adjusted everything manually.

I've been warned against auto-levels when shot with strange lighting, such as flourescents. Also been told to avoid it with flash. But daylight w/o flash, have you had any weird results then? Thanks.

DoctorIt

I agree with Cletus almost exactly. I use it from time to time, when making some quick fixes to not terribly important photos. Most of the time, I apply it, and then fade it back a bit in the edit menu. This gives me suprisingly good results and is super fast.

mercphoto

cletus wrote:

Auto Levels should help images with low contrast. It can also correct color casts. It can help brighten dark images, or darken bright images. The thing to keep in mind is that Auto Levels will work fine as long as it is making minor corrections.

Cool. Minor corrections are what I'm trying to accomplish, as the images are usually very close to what I want to begin with. Minor changes are a pain to do manually (seems not worth the reward/cost involved) but are good candidates for automating. I can see how it would not work for images that require a lot of processing to correct.

wxwax

mercphoto wrote:

I've been warned against auto-levels when shot with strange lighting, such as flourescents. Also been told to avoid it with flash. But daylight w/o flash, have you had any weird results then? Thanks.

Yeah, I virtually never use a flash.

Harryb

wxwax wrote:

All I can say is that after getting some weird results using Auto Levels, I stopped using it and adjusted everything manually.

The default values of Auto Levels are set to 0 (the "Black Point') and 255 (the "White Point"). Too often these settings are incorrect, they make shadows too dark and the highlights too light. One of local pros down here advised me to change these settings by:

Open an image and access the Levels dialogue box (Photoshop: Image - Adjustments - Levels; PSE: Enhance - Adjust Lighting - Levels).

Double click on the black eyedroper to open the Color Picker dialog box. Type in the number "10" in each of the boxes labeled R-G-B or type in "4" in the HSB list. Click "OK" in the dialog box.

Now double-click on the white eyedropper to reopen the Color Picker dialogue box. Type the number "246" in each of the boxes labeled R-G-B or type "96" in the box labeled "B" in the HSB list. Click "OK" in the dialog box.

Click "OK" in the Levels dialogue box, then click "yes" when asked if you want to save the new target values. This should improve the performance of Auto Corrections incluidng Auto Levels.