Essential Image Correction and Sharpening Basics

Proper color, contrast and sharpness can make or break the final look of an image. In this post I will show you some of the basic image correction and sharpening techniques used not only for photography, but also for use on the web.

Image Sharpening Using the High Pass Filter

Start out by opening the image in Photoshop, for this tutorial I used this image from stock.xchng.

Duplicate the image by pressing cmd+j (ctrl+j in windows) which will give us a copy of the image to go back to if anything goes wrong, then apply the high pass filter by going to filter > other > high pass and give it a setting of 9.3 and click ok. The image should now have gray discoloration to it.

For the final step, change the the blending mode to overlay, softlight, or hardlight, depending on what kind of effect or how much sharpening you want out of the image. For this example I used the hard light mode to give the photo a grungy, high dynamic range (HDR) look. As you can see from the image shown side by side, there is quite a big difference in the image quality on the left by simply adding a high pass filter.

You can get many different results from the image by setting the strength of the high pass filter to a higher or lower number or by applying a layer mask and using a black brush to cover certain areas and then lowering the opacity to get your desired effect.

Adjusting image levels, color and curves

A proper understanding of how to adjust the levels, color and curves of an image histogram will help you better represent tones in the final image.

Adjusting image levels

The levels tool can move and stretch brightness levels in a histogram using three main components: a black point, white point and midtone slider.

Going back to our original image, make a copy by pressing cmd+j (ctrl+j in windows). Then go to image > adjustments > levels and open the levels editor. On the histogram, adjust the black and white sliders so they touch where the histogram starts and ends then click ok. Our image levels are now properly adjusted.

Adjusting image curves

Similar to the levels editor, the curves editor can take input tones and selectively stretch or compress them. Unlike levels, which only has black, white and midpoint control, a tonal curve is controlled using any number of anchor points up to a total of 16.

To adjust the image curves, go to image > adjustments > curves and open the curves editor. Drag the top white slider and the bottom black slider to about 15% of their original position. The final settings should resemble the image below.

Color Correction

Bringing out the proper colors in an image can be easily done by using the color balance tool in Photoshop.

Go to image > adjustments > color balance and open the color balance tool. The image we're using doesn't necessarily need color adjustment, but if the image had too much green or blue you could adjust the sliders to a negative amount and bring the colors back to where they should be. I'm going to bring out a little more of the reds and blues of the image we're using by moving the red and blue sliders to give the image a little more pop.

With all of the techniques that were used, you can achieve different looks of your final image by setting different values in all of the tools that were used. How the image turns out is simply a matter of taste, and these settings are basically a guideline to get the optimal end product.