This is not a color correcting article for our objectives here is to explore some fun ideas and techniques for making changes to colors in your images without actually disrupting the overall balance as traditional color correcting tools like Curves would do. If you like, you may consider these techniques as pure fun where you can express your artistic creativity in a purely intuitive way. Note: the examples shown here in this article are designed to show the potential of this tool and may exaggerate the colors for demonstration purposes. They are not intended as examples of what you should do with images, especially the amount of adjustment. When working with this extremely versatile tool please use as much artistic discretion as possible!
But is this faking our pictures? Are we not altering reality? Do we really have the right to make changes, from subtle to outrageous, presenting our view of reality and not that of the camera? This is obviously a philosophical issue that only you can answer after carefully considering the consequences. Will your customers appreciate your changes? More important, will they pay you for them?! If you are practicing your skills in digital photographic art, then you can explore these techniques to your heart's content for you will obviously learn a lot about the capabilities and limitations of the system as well as what can be done with color images. HSL is definitely one of those tools that not only allows you to push the limits, it forces you to question philosophically just where the limits are or why there should be limits in the first place.
On a technical note, HSL can be very useful for returning images to the state of beauty you saw just before you clicked the shutter. Realize that the camera will do what it is programmed to do, not necessarily what reality existed at that moment. All digital photographic images are actually representations of the original scene and they don't always capture the full dynamics of color. Printing requirements require that there be no colors out of gamut. Those bright, saturated colors we will see in this article may not be printable. Printing presses do not reproduce the wide range of colors we see on screen. But, for you print technicians, is it possible to push your colors as far as possible within your limited color space making your images as bring as possible?
The objective is simple: if it looks good, it is good! This highly subjective control over color is meant to enhance images, make certain colors stand out, improve brightness and even turn a dreary cloudy day into bright sunlight. With HSL you can have the colors you want with just about any image. Well, if you can't, you can at least explore the possibilities!
Our tool of preference is Photoshop's Hue Saturation and Lightness dialog box (HSL) from 5.0 shown at far left and 3.0 at near left; both at reduced size. In this article we will use the 3.0 version. They both work about the same giving results that are visually equal. One difference is that in 5.0 the individual colors are on a pop-up list whereas they are on a radio button list on the left side of the 3.0 dialog box. When using HSL in any version (or HSL in other programs), your objective is to observe carefully the screen preview showing you the changes to your image. It is very important to watch the entire image carefully for you never know what part of your image contains that certain color you are adjusting.
It is also wise to have the Info Palette open on your screen. As you make changes, you should check the colors for a possible out of gamut warning as shown at left. Notice the exclamation after the adjusted CMYK colors (the column on the left is the original values and the ones on the right are the in-progress adjusted values). Study the numbers and there does not appear to be all that much difference, but enough to cause possible problems on a press. The color? A very nice sky blue. For web work it would be acceptable; not for print.
When you work, check other colors on your picture besides the ones you are adjusting. You may find differences in the color readings that may signal unacceptable results by producing unintentional color shifts.
Hue
You have to imagine the traditional circular color wheel that plots colors in a full 360 degrees. With hue you are changing all your colors relative to the color circle. Reds may shift into blue, and so forth. The best use of Hue is when you are correcting a photograph exposed to the wrong type of light. With silver film, if you used outdoor film indoors under florescent film the colors would all be too blue. Hue will make the colors appear more correct by shifting the entire color wheel. The results may not be perfect, but at least the excess blue will be minimized.
At left is our starting picture for this experiment, a red flower with bright green leaves. Although the colors are moderately accurate, with hue we could play some games with them and create some interesting effects.
Our first attempt is to adjust the Hue to make the red flowers a kind of violet shade by shifting the Hue -60 degrees (or 60 to the left on the Photoshop HSL Hue scale). Moving 60 degrees to the right (plus 60), by the way, turned the flowers bright green.
Now these flowers are definitely interesting! However, there is a serious problem; the nice green foliage is shifted in color as well and the leaves are not very pleasant. You see, with Hue you are shifting all colors in your picture.
But we have a possible solution. On the dialog box (version 3) there are a number of color chips on the left side with radio dials. Each of these colors allows you to adjust them independent of the rest of the colors. For example, Red allows us to shift the hue of the red colors without affecting other colors such as green. In version 5, you can select your color on the pop-up list at the top of the dialog box. In both cases "Master", the default, adjusts all colors at the same time and is the setting used on the strange flower shown at left.
You can, and probably should, explore some of the effects of shifting hues for each of the colors. If you don't like the results, return the slider back to zero (middle of the scale). Explore the possibilities of making subtle and slight changes to colors to enhance them without actually changing them. One final word of advice, if you are adjusting reds, all reds will shift! If you wanted just a certain object to change, you must select it with the Photoshop selection (masking) tools.
In this example, far left, we confine our hue adjustments to the Reds by checking the radio dial to the left of the red chip. We adjust the red sliders all the way, or minus 60 degrees. Notice that the individual channels only allow a plus or minus 60 degree adjustment while the Master setting allows for plus or minus 180 degrees.
If you insist on pushing the color further than 60 degrees, it can be done in two separate operations. First, red is shifted to magenta (click OK). Then select the magenta radio button (because the color you are adjusting is now Magenta and not red) and adjust again to produce the blue color (above, right). Notice in both examples, the green color is about the same. There is a possibility of slight tone shifts because the green color may contain a slight amount of red which will shift along with the flower colors. Always be aware of the chances that other colors may shift. What can you do about it? You could adjust the green radio button and make a slight correction.
There are six separate colors to adjust, Red, Green and Blue are the three primary colors used on our monitors and digital cameras. Cyan Magenta and Yellow are the three primary colors used in printing. All six are available each color 60 degrees apart from the next.
Note: we have had problems turning colors into yellow. They appear muddy and greenish or reddish but not pure yellow. Moving other colors seems to work but not yellow.
Saturation
Saturation, very simply, is the brightness of the colors. By increasing the saturation colors are made brighter and brighter. Eventually they will be unbelievably bright and which point you realize you have applied too much saturation.
An easy way to think of saturation is to look at the same natural scene (look out your window) under different lighting conditions. When the sunlight is very bright, the saturation is high and the colors very bright. If a cloud passes over, the colors are still the same but they are not as bright. The saturation is very low. The colors also appear different in the early morning or near twilight. With Saturation, the middle slider in the HSL dialog box, you can make a cloudy day look more like a sunlight scene just by increasing the saturation. You can also desaturate (lower the saturation level) a scene to eliminate any out of gamut colors that might not print on an offset press. Printing processes (this includes your inkjet printers) are not able to reproduce those nice bright saturated colors. The color will get just so bright and colors and those that are more saturated will be the same color as the maximum saturation of the ink. Pre-press technicians have to check for "out of gamut" (a special preview mode in Photoshop that helps you detect problem colors) colors and desaturate all the colors bringing them back into balance.
We can use Saturation to improve the overall look of a picture that was taken under less than perfect conditions. At far left we move the Saturation slider to plus 50 making all the colors very saturated (extra bright!). Compare this version with the one above. Notice something interesting? The gray colors are left unchanged. Neutral gray colors, from the white on the building to the gray wall to the almost black colors of the house are largely unaffected by saturation because they, well, have no color! It is only when one of the six primary colors is predominant will it be eligible for saturation. This can be very interesting but it can also be rather frustrating because they now appear out of balance with the oversaturated colors next to them.
Above, right, is the same picture with the saturation decreased to minus 60. Here the colors appear less saturated. Why would you want to do that? Maybe you don't like oversaturated colors. They are a bit unrealistic and a slight desaturation makes the scene more realistic. A second practical purpose is to use saturate and desaturate to balance the look of several different pictures. Say, for example, we were preparing a real estate ad with four pictures. Saturate/desaturate could balance the look of all four of them making for a more uniform layout.
We can also use saturation on one of the six individual colors and bring out certain colors in our scene. In the example at left we increase the red 25, yellow 30 and green 40. This brings out the green trees and generally warms the picture (red and yellow are the primary warm colors). The other three colors were decreased, cyan -20, blue -10 and magenta -25. Adjusting cyan and blue fine tunes the sky color. Since the grays could not be adjusted, the sky was toned down to keep the picture in balance. Many times cyan and blue are increased to brighten otherwise dull skies. (An additional hue adjustment was made to the red color moving plus 5 degrees toward yellow. The sidewalk started appearing too red.)
But why reduce magenta? It seems to be a characteristic of this particular Sony FD91 camera that magenta seems to bleed into surrounding colors. In this picture magenta was found in the building in areas that should be gray. Increasing the saturation of magenta left hits of pink in the fine woodwork and this is unacceptable. We generally reduce magenta in almost all pictures for this purpose. Rarely the magenta will be totally desaturated with no loss of color balance. Is there a possibility that magenta just isn't that predominant a color in outdoors scenes? Without comparing the results of this camera with other brands the results are inconclusive. But for now, magenta is generally reduced with our images; maybe not with yours.
When you make these adjustments using the individual colors, do not adjust the overall Master slider. Make your adjustments with the individual colors, usually starting with Red. Slide the triangle all the way to the right to plus 100 (shown at left) and observe where the colors are. Notice that there is a lot of red in the sidewalk but that some of the house contains red. We cannot make too much of an adjustment to the sidewalk before messing up the colors in the house. But notice that the sky contains no red and will be unaffected by our adjustments.
Now back off on the slider until you are pleased with the results. Watch these sensitive areas carefully and balance them with the other colors in the picture that contain no reds but other colors. Don't forget to explore the possibility of moving the slider to the left of the zero point to see the effect of desaturating this color.
Work on the next color, yellow and repeat the same procedure. First find out where the color is sensitive to saturation adjustments and then determine the amount of adjustment you would like. One at a time work each color. You may find that some colors produce little or no effect, probably because the picture contains no areas of that color. Leave it at zero and go on to the next color.
This could be time consuming and tedious but you do have the opportunity to fine tune your saturation. Combine this with the possibility of minor hue adjustments and you have a lot of possible options. Should you do this for each and every picture? The place to start would be to test the Master saturation level and see what the picture contains for possibilities. Remember that gray does not saturate so this may limit your options. Be careful when you approach a picture with a specific objective in mind. It may not be possible to make that adjustment. Instead, explore what the picture has to offer and then work within that confined adjustment range. The real skill is to push the colors to produce the look you want without making the picture look too faked.
Lightness
The lightness control allows you to adjust how light or dark the colors are. Actually in Photoshop this control seems to lighten or darken the entire image. Unfortunately, we have not found much use for Lightness. It can be used as a contrast adjustment but Curves is far superior where you can adjust different densities making lighter parts lighter and darker still darker. This is a far superior contrast adjustment that lightness offers. Think of Lightness as a contrast adjustment similar to Brightness/Contrast. Very poor control. Explore lightness when you need to lighten or darken a certain color a little bit. It may help but don't expect much results. Darkening a color shifts it toward a dark gray and not a deeper color. Lighten will shift toward white and give the color a faded look. This faded look does not appear to be adjusted out by increasing saturation.
An example
In this picture, shown at left, we use HSL to enhance the overall look of the colors and hopefully improve the picture. Start by studying the image carefully seeing which colors need brightening and which can even be desaturated to bring them back in balance. This picture has already been adjusted for levels and curves.
A preliminary analysis concludes that the picture is very blue but some brightening could be called for. The green colors need to be brightened to bring them out from the surrounding blue. The picture could be warmed a bit by increasing the saturation in red and yellow. This will add detail to the rocks and the yellow submarine parked in someone's front yard.
Start with an overall saturation of 50 on the Master color channel. This will give you an idea of the possibilities. The yellow submarine will be more visible but yellow showing on the building clearly indicates there is going to be a problem getting a bright yellow without affecting other parts of the picture. The red contents of the masts on the sailboat looks like an improvement. The rocks will be better. The trees show that they may be too yellow so a hue adjustment may be called for. The sky is brighter and shows a lot of possibilities for tailoring the colors. A problem seems to be in the side of the boat which should be white. Because of natural reflections it appears a bit bluish even in the original. More than likely, this will limit the blue and cyan adjustments unless a change in the boat color will be tolerated. As a last resort, it will be possible to use the Desaturate Tool on the the hull and Sponge away (desaturate) the blue in just this area. This handy tool can also be used to Saturate the yellow submarine without upsetting the colors on the building. Be sure and use the manual tools only if you cannot achieve the desired results using the HSL dialog box. Furthermore, try and limit your manual adjustments because they are time consuming, tedious and subject to throwing other colors out of balance which will require further hand retouching.
We start by adjusting the two warm colors, red and yellow, bringing out as much detail as possible. Here we increased red to plus 40 and yellow to plus 25. More yellow started to show in the building. More red did not make that much difference but beyond 40 it started to be too bright. After the other colors are adjusted, the image may tolerate more red but we won't know until then.
Also, magenta was desaturated top minus 50 because of stray pixels in the boat and building. On the plus side, no significant image appears in magenta so the loss of it is more of a technical advantage.
At left, green was increased to plus 25 bringing out the delicate green colors in the trees. A hue shift toward cyan was considered to improve the greenish color but it didn't seem to make that much of a difference so the slider was returned to 0.
At left, cyan was adjusted to plus 30 and blue to -15. The cyan seemed to brighten the sky more and the blue seemed to affect the color of the boat hull more than cyan. With less blue in the sky, the contrast of the sky and green trees is enhanced slightly.
Some work with the Sponge tool was attempted on the side of the boat but no significant improvement was made and Undo was used to return the image to its previous condition. If you are in doubt about the value of any adjustment, it is best to undo.
The final picture is shown at left. Compared to the original it is really not that significant a change but it is a subtle change. This is the primary use of HSL, not for noticeable changes but rather almost unnoticeable changes that make slight improvements. But how about the original scene? The wonderful blue color of the Grand Cayman waters is simply not possible; you simply have to be there to see them in real life! It is a kind of iridescent color that cannot be duplicated with any photographic system. Other than the bluish cast to the side of the boat, the colors are fairly representative of the original scene.
Conclusion
Is HSL something you would do with every picture or just a tool to use for special purposes? Perhaps if you can work the extra time into your production schedule, it would always be worth opening HSL and, if nothing more, move the Saturation slider to something like plus 50 just to see what potential the picture contains. From there, it is an aesthetic, philosophical and production issue whether you spend some time and explore possibilities. When you make adjustments, be sure and test the desaturation of a color to bring it back into balance with other colors. It may be a mistake to always increase saturation to achieve your results. Don't forget to test a hue shift for each of the colors. Many blue skies and green trees respond well to hue shifts. Yellow grass, the kind that hasn't been watered for a few weeks, will come back to life with a slight hue shift toward cyan. Over time you can discover such solutions and apply them to many of your images you work with on a regular basis.HSL is just another collection of techniques for adjusting your picture. Be it correcting for poor photographic conditions, enhancing details by the use of color contrast or simply exercising your artistic license, they are controls worth considering and working with. But when you work with this complex set of adjustments, be sure and leave no color unadjusted. You may be very surprised what you can discover with the move of a tiny triangle on a very powerful dialog box.
