But this idea is incorrect. Sharpening may be able to correct these existing problems, but it was originally designed to solve the problem of digitalization - converting a scene or image on film from continuous tonal areas to small squares of specific tones. As far as DC is concerned, when capturing images digitally, if the lines of details coincide with the elements of the CCD, they may be too small to be recorded by the CCD and converted into corresponding pixels for expression. In order to avoid this situation, DC blurs the situation so that details (lines) can be recorded across several pixels. The blurred image details are actually "hidden", and sharpening restores these details by increasing the contrast between adjacent pixels. If details (lines) are smeared out by more than 4 pixels, sharpening will create sharp image edges by increasing the contrast between adjacent pixels.
Although there is often a sharpening option in digital cameras, we still recommend that you adjust the pixels yourself and determine the sharpening effect of edge details and textures according to the actual situation of the photo. At the same time, it is best to pay attention to one thing, which is at the end of photo processing. Do the sharpening, not in the beginning and in the middle.
Original image: Shot with Fuji F700
In addition, we must note that JPEG is a lossy compression format, so it is best to convert it to a lossless image format before processing the image. This is often the first step for photography masters to perform post-processing. Convert JPEG to TIFF format before processing. Pay special attention not to save the same photo in JPEG format multiple times. If you really want to save it, please use Save As. ..Order.
If you would simply use the SHARPEN filter in Photoshop and simply repeat it 5 times, you would get the following photo. The fact is that the sharpening filter is a blunt tool, and the sharpen MORE (further sharpening) filter is similar. There is no more use than saving the number of repetitions.
The SHARPEN EDGES sharpening edge filter is slightly stronger than the previous two, but it still lacks flexibility. If used in large quantities, it can easily lead to pixelation of the image and white edges. This tool selects before increasing the contrast, finding pixels that are large in the image and have significant gaps between adjacent pixels. The difficulty is that the program often doesn't correctly figure out where the edges are. If you're photographing a clear object in front of a simple background, this filter works brilliantly. But if there is more detail and the skin tones contain more contrasting pixels than you think, this is where the edge-sharpening filter becomes more difficult.
The Unsharp Mask (USM) sharpening filter is commonly used by us and is also an almost universal tool, because it can quantify the degree of sharpening through 3 ways, quantity, radius, and threshold.
The unsharp masking (USM) process in Photoshop provides three control parameters:
Amount (Amout): Controls the intensity of the sharpening effect. For general processing, a setting of Amount 150 Radius 1 Level 2 is a good start, then adjust as needed. If the quantity value is too large, the image will become artificial.
Radius: used to determine the width of pixels for edge emphasis. If the radius value is 1, then the entire width from light to dark is two pixels. If the radius value is 2, then there are two pixels on each side of the edge, so the entire width from light to dark is 4 pixels. The larger the radius, the clearer the difference in detail, but at the same time, halo will be produced. Professional designers generally prefer to use USM sharpening multiple times rather than setting the sharpening radius to more than 1 pixel at a time.
Threshold (Threshold): Determines how much contrast the adjacent pixel boundaries can be sharpened, and below this contrast value no sharpening will be performed. The setting of the threshold is a key parameter to avoid problems such as spots and pitting caused by sharpening. When correctly set, the image can maintain a smooth natural tone (such as a pure blue sky in the background) while maintaining a perfect image. The contrast of changing details can be emphasized. In general prepress processing, we recommend a value of 3 to 4. More than 10 is not advisable, as they will reduce the sharpening effect and make the image look ugly.
Although good sharpening effects can be obtained by just using the default parameters, it is always necessary to use more and compare, and to set reasonable sharpening parameters according to the actual situation, so that the image details can be reproduced better without causing new artifacts. Trouble: Such as spots and pitting.
Generally for portraits, you need parameters with a small number, wide radius, and high threshold. The commonly used parameters are 71/17/17. For landscape images with a lot of details, you need parameters with a high number and low radius and low threshold to show the details, such as the 200/2/2 set of parameters.
Although these parameter settings are commonly used, they are not absolute. You need to adjust them according to your own needs. If you oversharpen, you'll notice a halo around the edges of the object, like using a torch to draw an edge line around the character. If you continue to sharpen the entire photo will become pixelated.
If you need to process landscape photos quickly and in batches (equivalent to the SHARPEN command), you can set the quantity to 80, the radius to 2.2 pixels, and the low threshold. To sharpen portraits, set the threshold to 10.
In the action collection provided by PAA, there are several actions for sharpening. They are each subtly different. You can try more, but they basically use the USM sharpening filter. Some detailed instructions for the "sharpening-LAB method" are given below.
Sharpening LAB method
The processing method used in this action is also a common daily Photoshop sharpening technique. It is to first convert the RGB image to LAB mode through the "Image Mode" command, then select the brightness (Lightress) channel in the "Channel Panel" and use USM Use the sharpening filter to sharpen the image, and finally convert it back to RGB mode. The advantage of this is that it avoids the dispersion problem that appears on the edges of the object after sharpening.
Default parameter settings of the USM sharpening dialog box (the image of the brightness channel is displayed in grayscale)
Have you noticed that the image in this dialog box is black and white? That’s right! :)
Below we give some other commonly used USM sharpening parameters for your reference:
× Amount 150%, Radius 3 pixels, Threshold 1 Level, suitable for softer images (portraits or flowers).
×Quantity 85%, Radius 1 pixel, Threshold 4 levels, suitable for most situations.
× Amount 65%, Radius 3 pixels, Threshold 2 levels or Amount 65%, Radius 4 pixels, Threshold 3 levels, strong sharpening effect, suitable for subjects with sharp edges, such as buildings, coins, cars, etc. Or the photo itself is blurry.
The sharpening effect after using this action twice is as shown in the figure.
Another trick here is to use the "fading" menu command to get the desired effect. For example, if you find it is a bit too sharp after sharpening, you can use this command to fade it a little. You can set this percentage yourself.
The four tools were introduced earlier. In fact, the sharpening process is a process of controlling contrast, so one of the most effective ways to select sharpening is to apply layer + high contrast preservation filter. First copy a layer, then use the "High Contrast Preservation" filter on the copied layer, and then adjust the overlay method of the layer. For example, if you want the color to be richer, you can use "Hard Light"; if you want to sharpen it, use "Soft Light" "; For a stronger effect use "Bright" mode.
There are also some techniques that use masks or selections to sharpen parts. I won’t go into details here, but the specific steps are almost the same.
The last method is easily overlooked. In order to sharpen the subject, we can blur the non-subject. For example, for a red flower among green leaves, after sharpening the entire photo, we can blur the green leaves (using the blur tool), and the red flower will look more beautiful.
In addition, sometimes it is also a good choice to directly use PS’s sharpening brush to sharpen.