Photoshop for beginners - understanding levels and curves input values

If "Tone value correction" dialog box, you set the value of the input or "Curves" either by the black or white triangular slider drag or enter a value directly in the input box, you are to say Photoshop, all the pixels in the image change, the new sound value, so that the same as the standard output value. For example, if you move the white slider in the dialog box "Curves" to 250, you say basically "I want all pixels with a value of 250 and higher (i.e. 250 to 255 range), have the same value as displayed in the field output."

As is the standard output value 255 for white, all the pixels in the image with a value of 250 or higher take place, be pure white (value 255). The other light tones in the image will be easier. The same goes for the black slider. If you move the black slider, you set the INPUT value all pixels with this and lower value equal to the standard output value changes is (i.e. black) of 0. For example, if you move the black slider or you set the input black value to 25, are all pixels with a value of 25 or lower on the output value from 0 (black) provided. This is also all the shadow tones to the darkening of lead.

Actually, you are the upper and lower limits of the white and black tones in the image which in this example would increase the overall contrast of the image. So, if you have a low contrast image that still didn't get a black clay and has not got a white tone, you would normally speak his "OK, the darkest tone in this picture has, say a value of 20, but this is not true black and I want it to be black." "Right, so that I must have the INPUT value, set the black slider to 20 and leave the output value with 0."

This changes the value of the selected audio from 20 to 0, which is the depth of the shadow tones. Note that all sounds in the dark areas are proportionally be reduced in value. You have one now either levels or curves sound setting 'has assigned the value of 20 to 0'. Working with the lighter tones now, we say the lightest tone in this same image has a value of 230 (a light gray photos sound, typical for low contrast). Now let's assume, we want the image to a pure white have. So, we need to change the value of this tone of 230 so that it looks white (value 255). Use the levels or curves adjustment dialog we move the white slider until the INPUT value 230 is and let the output value to the default value of 255. This will change all sounds with a value of 230, so that you the new value of 0 (zero) have that white in the image change is.

The result of these two changes to the black and white input values are that the image contrast have increased you, thus it fill the full tonal range and more ' normal' displayed. Now you understand levels as the input values in the dialogs and curves work and correct as you use it, take a picture with low contrast.

Now on other features in Photoshop learn by the accession of me and other like-minded folk, free of charge Zone2Tone members , and after you get us free professional-quality video tutorial.

Copyright (c) Les Meehan 2010.

Les Meehan is the author of seven published digital photography books and as a qualified teacher workshops taught for over 20 years.

Photoshop for beginners - understanding levels and curves output values

In another article, I explained how the INPUT values, which uses the dialogs Photoshop layers and curves. In this article I discuss the output values except to say that are the default values of 255 for the white slider and 0 for the black slider.

The output values can be used, darken lighten up dark tones to bright colors. This can be used to reduce the overall contrast of a photo. When you drag the black endpoint on the left side of the diagram upwards, you will be in the curves dialog the value of the black output for the default value of 0 (zero) increase. Conversely, if you drag the white end point on the right side of the chart down, you can reduce the value of the white output to less than the default of 255. This has the effect of reducing the contrast of photography that you edit. This is similar to, but to the using the input values.

However, the output values have a more important function - you help you calibrate your printer! If we print thumbnail the images are interpreted by the printer, and this can all too common problem to which the pressure not matching the image result. The problem is that the printer has an own ' contrast range' and this may be, and often is, less than the contrast of the screen of image.

This means, that the printer well some which are more subtle tones of the image, that is, shadow values 5, 6, 7 to say 15 as black and print the lightest tones of 250 251 up to 254 as solid white. The result would be a pressure, which had more contrast and less detail than the image.

The solution is, some test to make prints with a gray scale of sounds (i.e., a number of patches of different sound values) from black to white. The tonal values of each patch should be in the value of say 3 or 5 in both the brightest and darkest parts change. The middle tones can such as units of 10, since you are not so important with larger differences in values that change this calibration. You print on this scale your printer with your usual papers. You should test each paper that you use as the paper of the visible dynamic range effect.

Now, compare the pressure on the screen and find the sound value patch on the printed scale, which is completely black and that is entirely in white. For example, you need dark tones in the grayscale screen 0 (black) say image, 5, 10, 15, 20 and bright sounds say 250, 252, 254 and 255 (white).

If the view of the test is print, if there is no visible difference between the dark it spots the scale with values of 5, 10 and (i.e., the notes of 5 and 10 are pure black in print) shows this black your printer on a dark tone which interpret value 10 and less than pure black.

Which will look at lightest tones, vice versa, if the notes with values 252 and show white paper, your printer shows this to something about 252 as pure white as printed. Well, now we the borders the contrast can know the printers can produce. In this example, every note is printed darker than 10 as pure black and white prints each sound lighter than 252 as pure.

Now we can use the output values of the dialog window curves, to compensate for this printer/paper contrast. With our example, we now know that every note with a value of 10 or lower are black in print. In other words, is the BLACK POINT of the printer 10. Yes, to compensate for the output value, we need the the black slider in the curves dialog box set to the value 10. This is the shadow in the image lighten (and probably make it boring look), but when you print the image of the printer will lower the values below back where you you.

The same happens for the lighter tones. The printer will produce any value of 252, such as paper white (no ink), so we need to output value, which the white slider in the dialog curves 252 set. This reduces the values of the light tones in the image, but the printer will lift you back up to the expression! You are now enough the levels and curves output values for you the image contrast options to customize the printer and paper. The Visual result on the screen does not matter!

Now on other features in Photoshop learn by the accession of me and other like-minded folk, free of charge Zone2Tone members , and after you get us free professional-quality video tutorial.

Copyright (c) Les Meehan 2010.

Les Meehan is the author of seven published digital photography books and as a qualified teacher workshops taught for over 20 years.