Fast, Easy Pop Art With Lab Color In Photoshop

Step 4: Apply The "Posterize" Adjustment To The "b" Channel

Click on the "b" channel in the Channels palette to select it. Again your image will turn gray in the Document Window. Just as we did with the "a" channel, go up to the Image menu, select Adjustments, and then select Posterize. Once again enter 4 for the Levels option:

Click OK, then click back on the "Lab" channel in the Channels palette to view your image after applying Posterize to the "b" channel:

Step 5: Apply The "Gaussian Blur" Filter To The "b" Channel

Click on the "b" channel again to select it. We're going to smooth out the colors in the "b" channel just as we did with the "a" channel, so go back up to the Filter menu, select Blur, and then select Gaussian Blur. Enter a Radius value of 4 pixels once again and click OK:

Click back on the "Lab" channel to view your image after applying Gaussian Blur to the "b" channel. Once again, the colors are now much smoother across the image:

We now have the colors for our effect. We're going to adjust the lightness values next.