Photo Editing 101

[TW]

One of the great things about J2 is that we exchange information on so many different topics. Over the last few days I have been thinking about starting a thread on basic photo editing to help those that are interested in, or just now getting into photo editing. We have a number of people on the board with editing skills and their input would be most welcome. If you have questions, ask, and we will try to give you answers that you can use in the real world. With that being said, on to the first lesson.

Photographs are Two Dimensional

Photos only have height and width, they are flat and have no depth. The image depicted in the photo is what give the illusion of depth. This illusion is dependent upon several factors. The first and most important thing is the presence of shadows and highlights. Shadows and highlights give the illusion of shape. Try to avoid taking a picture with the light source is on the same plain as the camera lens, i.e. the sun directly behind you, etc. This will result in little or no shadow and too much of the subject highlighted. Try to keep your light source at an angle, I try to keep it 30 > 60 degrees to one side or the other. This will put one side of your subject in shadow while highlighting the other side, with your mid-tones in the center. To demonstrate this here are two pictures of my car, in the first I have removed all shadows and highlights from the body.



Now with the light source, in this case the sun, positioned off plain to the camera.



The result is the presence of shadows and highlights that give the body of the car shape, contour and detail.

A picture that has either to much shadow and not enough highlights, or to much highlights and not enough shadows can be adjusted to some degree with the brightness/contrast adjustment. Having a good shadow/highlight relationship also helps establish a better depth of field, which is what I will cover next.


TW

[Ilovebigcats]

There is a guy named Donnie on Youtube that does a series called, You s**k at Photoshop.

It is HILARIOUS and very informative. I learned a lot watching it. It is very entertaining... for us sinner folk. lol I wont post the link here.. if you want it, you can PM me. MoleJ and Brewer would like it, if that tells you anything.

[TW]

Today I want to talk about “depth of field.“ Depth of field defines the distance range where things have an acceptable level of sharpness. What is an acceptable level of sharpness? The text book answer is something called the Maximum Permissible Circle of Confusion. It is based upon viewing a 8x10 photograph from a distance of one foot, the eye should be able to distinguish four lines per mm, or 0.25 mm per line. This is the Maximum Permissible Circle of Confusion. There is a formula for determining this CoC:

Maximum Permissible Circle of Confusion = sensor diameter / print diameter / print resolution.

For all intent and purposes though, the acceptable level of sharpness is subjective. What I want you to realize is that a camera’s lens can only focus on one point when taking a picture. That point will have the highest level of sharpness in the picture. The farther away, either in front of or beyond that focus point, the more blurred objects will become (a larger Circle of Confusion). In the following demonstration the circle in the center represents the object upon which the camera is focused, The circles to the left represent objects closer to the lens, while the circles on the right represent objects farther away. Circles 2 and 4 would be the Maximum Permissible Circle of Confusion. Circles 1and 5 have become extremely blurred as they are a greater distance from the point of focus.



Most people have point and shoot cameras. These cameras, while making it easy to take pictures, lack the ability to be focused manually. They are auto focus. They will focus on the closest object directly in front of the lens, whether this is the subject of the picture or not. When taking pictures, particularly landscapes, try to avoid any branches or such being in a direct line with the point you wish to focus on. The camera will focus on that branch and the rest of your picture will be blurred to one degree or another. If this happens it can be compensated for somewhat in the editing process.

To restore some sharpness in a blurred image try adding a little more contrast, usually in the middle tones, then use your “sharpen edges” filter. Do this gradually, as the sharpen edges will quickly cause the picture to become grainy, with a lot of “noise.” “Noise,” for those that do not know it is when you start getting a lot of white dots in your picture.


TW

[oletimer]

Thanks TW and keep it up.

[TW]

This is going to be a long lesson so I am breaking it down into two parts.

Part 1 - Histograms

In this lesson we will apply what we have already covered, plus we will learn about Histograms. A Histogram is nothing more than a bar graph depicting the distribution of the pixels in your picture. Histograms can be generated that reflect the tonal value of all the pixels regardless of color

or of the colors themselves

or even the luminosity of the pixels
.

Histograms are probably one of the most under used tools available to the amateur photographer. This is probably because people do not understand them. They are really quite easy to understand. All the pixels in you picture have a tonal value between 0 and 255, the computer simply counts the pixels according to their tonal value then generates a graph that depicts the various values.



If you divide the Histogram into quarters, and group the middle two quarters together it will look like this.



The Histogram will always arrange the values from the darkest on the left to the lightest on the right. So the first quarter are shadows, the middle two quarters are the midtones, and the last quarter are highlights.



The higher the column the more pixels it represents.

OK, now I’m going to edit a picture using everything we have covered so far.



This is a nice enough picture in and of itself, however I think that it can be improved to some degree. I will generate a Histogram, in this case the RGB channel (all the pixels regardless of color), which will help me determine how to improve the picture.



The Histogram confirms that this is a good picture, there are shadows and highlights, and there is an abundance of midtones. What the Histogram shows is that there are no deep shadows.


TW

[Gerald Creasy]

Histograms have always befuddled me. I look forward to learning.
(ANd if my Photo restoration attempt spearked this thread just come out and say "You"S**k at photo editing.")

[MacUser]

My photo comment for today:
Never EVER EVER EVER trust any image (or video) you see.

Regardless of the source.

[TW]

No my friend, your photo restoration project did not spark this thread. Although I do admire the work that you have done on that restoration. Photo restorations are a very tedious, time consuming projects. You have done an outstanding job with yours.

You said that Histograms have always befuddled you, I used to have the same problem. Histograms are nothing but a bar graph the depicts the number of pixels of any of the 256 shades of a color that is used in digital photography. The darkest shade (black) is on the left and represented by the number 0, the lightest shade (white) is on the right and represented by the number 255. Between them are 255 shades of gray (or red, green or blue). If you were to stack up all the pixels in a photograph according to their shade you would have a Histogram, the computer does this for you. Now the height of a Histogram is very flexible because it is dependent upon the number of pixels in the tallest column. This tallest column is always assigned the value of 1 (not the shade 1, the value of 1) all the other columns are then related as a decimal fraction of the value of 1 (the tallest column). In the Histogram bellow the yellow arrow is the tallest column, it therefor becomes 1, no matter how may pixels there may actually be in that column. The red arrow is only 1% of the yellow arrow so it is 0.01, the green arrow is 48% of yellow or 0.48, and the blue arrow is 0.33. A histogram simply tells you how your pixels distributed as far as their shades are concerned. It will not tell you where in your picture they are, but it is pretty safe to say that the darkest shades will be shadows, and the lightest will be in the highlights.



I hope that helps.


TW

[TW]

It is now time to edit this photograph using what we have covered so far. The first thing I would recommend is that you make a copy of your original photograph give it a different name and do your editing to it. That way if you mess up and can't get the photo your working on corrected, you can delete it and still have the original to go back to. Another thing is that if I am going to post a photo I will resize it to 600 pixels in width, that is a good size for boards such as this, it's not too big nor too small.

I started the editing by evaluating the picture with the aid of a Histogram. the Histogram showed that there was a lack of the dark shades (shadows). To correct this I used went into the Enhance Menu/Adjust Lighting/Brightness and Contrast. Click on Brightness and Contrast to bring up a pop up box.



I have gotten to where I prefer to type in the value that I want to change rather than use the slider bar, I feel that it gives me better control. I Brightness I typed in -5, meaning that I wanted to shift the Histogram (brightness) 5 shades to the left.



If you look at the Histogram under the photo you will notice a ghosted area, that shows the amount of shift. While it may not look like a major change, I believe that it will be enough. I suggest that when making changes, do so a little at a time. I think that you will find your end result will be better.

Now that I've established a little more dark shades I want to increase the contrast. Again in Enhance/Adjust lighting/Brightness and Contrast drop down box I typed in the amount that I want the contrast to change. To be honest I first typed in the number 3, I didn't like the result so I changed it to 4, and so on until I reached 9. At 9 I was content with the result so I saved it at that point.



Now the photo is looking real good, but I'm going to give it a little more "POP." In the Filter Menu scroll down to Sharpen/Sharpen Edges. I clicked on it once. I actually clicked a second time but did not like the results and had to undo the second click.



Now look at the Histogram and compare it to what it was when I started. A couple of very small change have made a great deal of difference in the distribution of the shades in the picture.

Now here it is at the start and when the editing was finished,




TW