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	Unsharp masking - Wikipedia, the free encyclopedia
		Unsharp masking is an image manipulation technique now familiar to many users of digital image processing software, but it seems to have been first used in Germany in the 1930s as a way of increasing the accutance, or apparent sharpness, of photographic images.
		The unsharped mask is then combined with the negative, creating the illusion that the resulting image is sharper than the original.
		In traditional photography unsharp masking is usually used on monochrome materials, however special panchromatic soft-working fl and white films have been available for masking photographic colour transparencies.
	en.wikipedia.org /wiki/Unsharp_masking (772 words)

	Unsharp Masking in the darkroom
		Unsharp masking is a technique that probably most of us have heard about but not many of us have tried.
		After the making of the mask (or perhaps I should say masks, as it is possible to use them in combinations) you will then sandwich the original and mask together in a registration carrier and print the combination as a single print.
		The advantage of this mask is that you may alter the overall contrast of a specific range of densities in the print with very fine control of those specific areas and have it be repeatable with accuracy.
	www.largeformatphotography.info /unsharp (6287 words)

	Contrast Masking Kits, Pin-Registration Carriers, Photography Workshops
		A contrast mask is typically a sheet of film (usually made by contacting the original negative on it in various ways depending on the desired mask) placed against the original negative when printing, or printed separately after the original negative is printed.
		The "mask exposure" that is given to the printing paper is usually done after the main (original negative) exposure is given to the paper.
		Because of that, this is a preferable mask to use instead of the Unsharp Mask when a sharpness enhancement is not of primary concern.
	www.maskingkits.com /maskingbasics.htm (1279 words)

	Unsharp Masking. What, why, how and when to apply.
		Unsharp Masking (USM) is the process whereby the edge contrast is increased in a digital image.
		Unsharp masking increases the edge contrast by finding the areas in the file where changes in colour and density occur and then creating an increase in contrast in the transition areas.
		However when unsharp masking is re applied to a pre-sharpened scan you lose detail, increase grain or "noise" and end up with a digital file of lesser quality.
	www.marinethemes.com /unsharpMasking.html (753 words)

	Sharpening Using an Unsharp Mask
		Unsharp masks are probably the most common type of sharpening, and can be performed with nearly any image editing software (such as Photoshop).
		Note: The "mask overlay" is when image information from the layer above the unsharp mask passes through and replaces the layer below in a way which is proportional to the brightness in that region of the mask.
		Normal unsharp masks increase the over and undershoot of the RGB pixel values similarly, as opposed to only increasing the over and undershoots of luminance.
	www.cambridgeincolour.com /tutorials/unsharp-mask.htm (974 words)

	Real Digital Unsharp Masking
		Unsharp masking is an advanced technique used originally in the graphics industry.
		In Photoshop, the unsharp masking filter is set up to be more of a sharpening filter, and is usually used to regain sharpness lost in the scanning process.
		Below, an unsharp mask is applied to an original image that has been previously enhanced with the SMI (Screen Mask Invert) technique.
	www.astropix.com /HTML/J_DIGIT/USM.HTM (1052 words)

	How Unsharp Masking and Laplacian Sharpening Work (Site not responding. Last check: 2007-10-31)
		Scaling the mask by a coefficient before adding it to the original increases the degree to which the Mach bands are pulled away from the original brightness curve.
		When using an unsharp mask you must pick a single pair of blur size and mask intensity for the entire image that you think has the most beneficial effect.
		By strengthening a mask in a "low" layer corresponding to a large blur, you increase the Mach bands in really large features (which I have noticed has the qualitative effect of enhancing contrast and saturation of an image as much as it sharpens).
	www.cs.unm.edu /~kwiley/astroPhotography/imageSharpening.html (1061 words)

	SeamlessTG - New Sharpen Algorithm! (image heavy)
		Unsharp masking is an old photographic technique where one makes a blurrier version of an image and then subtracts that from the original, producing an image where the edges made brighter on one side, and darker on the other.
		Unsharp masking is called unsharp masking because it has its origins in photography.
		Unsharp masking works by taking the original image, applying a gaussian blur, then subtracting that from the original image to produce a high pass image which is then multiplied with the original image.
	www.blitzbasic.com /Community/posts.php?topic=45962 (1765 words)

	[No title]
		The unsharp filtering technique is commonly used in the photographic and printing industries for crispening edges.
		In that case, because the mask peak was positive, the edge image was \ref{pixsub}{subtracted}, rather than \ref{pixadd}{added}, back onto the original.) \fig{lapmasks}{Three discrete approximations to the Laplacian filter.} With this in mind, we can compare the unsharp and \ref{log}{Laplacian of Gaussian} filters.
		In comparing the unsharp mask defined using the Laplacian with the LoG, it is obvious that the latter is more robust to noise, as it has been designed explicitly to remove noise before enhancing edges.
	www.cee.hw.ac.uk /hipr/src/unsharp.hpr (1210 words)

	Large Format Forum: Unsharp Masking
		An unsharp mask is a form of contrast reducing mask, the effect of which is to allow you to make the print at a higher contrast than normal, thus improving apparent sharpness and also improving local contrast especially in the shadows.
		After exposing the mask you let it dry, then put the negative and mask together using the pin registration system that you used to make the exposure and tape them together at one end.
		Henry, The reason that the masks are called unsharp is that they are made with the mask film and the camera negative separated by their respective bases.
	www.photo.net /bboard/q-and-a-fetch-msg?msg_id=0045bs (886 words)

	Basic Sharpening in Photoshop
		If you are using the Unsharp Mask filter for 'creative sharpening' it will most normally be in the range 60-150%, but when applying 'output sharpening' for print you may need rather higher values.
		Some people prefer to use unsharp masking not on the RGB image, but to convert this to a LAB image and sharpen only the lightness channel.
		Since the Unsharp Mask filter can only be applied to one layer at a time, you might need to merge layers or flatten your file to sharpen all image layers in a multilayered file.
	facweb.cs.depaul.edu /sgrais/basic_sharpening_in_photoshop.htm (2006 words)

	RetouchPRO - Manual Unsharp Masking p.133
		I tried running through the steps for manual unsharp masking using the image lily.psd included on the cd, and it ruined the vibrancy of the color.
		Susan S. The manual "unsharp masking" is duplicating the photographic process- not replicating the unsharp mask filter of Elements.
		To quote Richard what this manual unsharp masking does is "to increase shadow detail and give a sharper look to the image" On the lily image that you used this on the shadow detail is already fine - reduction of contrast in the overall image is not what is required.
	www.retouchpro.com /forums/printthread.php?t=7632 (701 words)

	Spatial Filters - Unsharp Filter
		Some unsharp masks for producing an edge image of this type are shown in Figure 6.
		The unsharp filter is a powerful sharpening operator, but does indeed produce a poor result in the presence of noise.
		Investigate the response of the unsharp masking filter to edges of various orientations.
	homepages.inf.ed.ac.uk /rbf/HIPR2/unsharp.htm (1116 words)

	Unsharp Mask
		The one on the left was sharpened slightly with PhotoShop's unsharp mask command and adjusted for brightness and contrast using the LEVEL settings.
		Jerry Lodriguss has an excellent collection of articles on CCD imaging, one of which clearly explains the use of unsharp masks for improving the dynamic range in images of deep sky objects and is obviously applicable to planetary images.
		An UNSHARP MASK was made and applied 3.0 radius for the blur, and -63 for contrast, -45 for brightness.
	www.fortunecity.com /victorian/canterbury/222/unsharp.htm (678 words)

	Contrast Masking Kits - Achieve ultimate print quality!
		Masking adds the further benefit of local contrast control (altering contrast within specific areas of the image) and when used in conjunction with variable contrast papers the techniques of obtaining stunning print quality are practically limitless!
		A new Inkjet Dodge Mask folder on the CD includes Photoshop actions to automatically generate an inkjet dodge mask for applying to shadow areas or highlight areas and a color file to make your own inkjet dodge mask for local contrast control when using variable contrast printing papers.
		Not only do you provide the text description of various masks and their application but you also provide the registration pins and material to actually construct the registration contact printer/negative carrier that is required.
	www.radekaphotography.com /maskingkits.htm (1783 words)

	Prepress Double Overlay Masking tutorial
		These faint positive masks are then placed onto the negatives of the other colours, so increasing the density where the pigments would already contain colour the same as that of the masks source colour.
		A yellow mask is also placed on the cyan negative, with the magenta mask, to increase the density where yellow pigment would print with the cyan pigment (greens).
		Using the other combinations of masks, the steps are repeated for the magenta and yellow negatives correcting (or evening out) much of the pigment errors, when printed.
	www.dtp-aus.com /dblovrly.htm (652 words)

	Digital darkroom - Composites by examples
		The goal of the unsharp mask is to increase the contrast of your original image.
		So using a mask with an intensity of 100 for example from the center to the edge will be most of the time useless, excepting to reduce the overall contrast or brightness of your image.
		Usually the resolution of a gaussian unsharp mask is in the range 3x3 to 7x7 pixels, showing a square shape, the most common and easiest shape available in imaging programs.
	www.astrosurf.org /lombry/digital-darkroom-examples.htm (2042 words)

	Dr. Dobb's \| Algorithm Alley \| July 22, 2001
		Unsharp masking is a photographic technique that increases the sharpness of a photographic image.
		This unsharp mask is very faint; in this particular case, the maximum value is only about a hundredth of the peak magnitude of the original.
		This is an important observation; for example, the "Unsharp Mask" script included with version 1 of GIMP (http://www.gimp.org/) builds an unsharp mask using 8-bit graphics operations, which severely limits the enhancement you can obtain.
	www.ddj.com /184411109 (1316 words)

	The Helix nebula, NGC 7293
		To reveal the detail and structure in the original plates a process known as unsharp masking has to be used.
		The picture above was made without unsharp masking, while the images AAT 15 and AAT 15a were made with the aid of unsharp masks applied to the same plates that produced AAT 15 and AAT 15a.
		Unsharp masking emphasises the smallest of the radial blobs inside the red shell, which are about 150 astronomical units across (150 times the Earth-Sun distance).
	www.aao.gov.au /images/captions/aat015b.html (281 words)

	Sharpening using Image Magick
		This tutorial is mostly for those who already understand the basics of unsharp masking and want to understand how to manipulate and interpret the parameters of the operator in Image Magick.
		Missing parameters to the unsharp mask will take on default values, which may not be the ones you want.
		Unsharp masking, like many other image-processing filters, is a convolution kernel operation.
	redskiesatnight.com /Articles/IMsharpen (1687 words)

	Photocritic.org article - Unsharp Mask Explained
		The Unsharp Mask is an old photography trick that has become available to 'the common man' through the introduction of digital editing tools such as Adobe Photoshop.
		This mask was a blurred (unsharp...) version of the negative, hence the name; Unsharp mask.
		The strength of the manual mask can be controlled through the amount of blur, the contrast of the layer, and the opacity of the layer.
	www.photocritic.org /articles/usm.php (2287 words)

	Understanding USM
		The principle behind unsharp masking is exaggerating the light-dark contrast between the two sides of an edge.
		One wants to take a piece of masking tape, lay it down along one's best guess where an edge should be, then colour everything on one side scarlet or dark green and everything on the other side pea soup green.
		To create an unsharp mask in a wet darkroom one creates a blurred negative of the original, then overlays the two, then creates a final print from that.
	www.luminous-landscape.com /tutorials/understanding-series/understanding-usm.shtml (967 words)

	Unsharp Masking - Large Format Photography Forum
		The definitive reference on unsharp masking is probably the articles written by Mark Jilg and Dennis McNutt.
		For an unsharp mask to work, it must be sandwiched with the negative between pieces of glass.
		Simplest arrangement would have the emulsion of the mask contacting the base of the negative, which is how the mask was exposed in the first place.
	www.largeformatphotography.info /forum/showthread.php?t=5728 (1211 words)

	Homework (Site not responding. Last check: 2007-10-31)
		The first thing I tried was straightforward unsharp masking, as suggested in the assignment.
		I implemented a spatial averaging filter and used it as part of the unsharp masker.
		The images on the right are with the unsharp mask applied to this image.
	www.columbia.edu /~alb63/4830/hw4/hw4.html (512 words)

	MASKING.htm (Site not responding. Last check: 2007-10-31)
		Unsharp Masking allows one to reduce the overall large-scale contrast of an image while retaining the local contrast of small details within the images.
		While a major improvement in masking capability occured in the move to PShop 3.0 (and 4.0) this is still not totally suitable for astronomical images.
		A good mask needs to show virtually NO residuals of these stars in the field and the perfect mask would show no sign of the stars.
	www.frazmtn.com /~bwallis/masking.htm (409 words)

	Cafe ILFOPRO - Unsharp Masking (Site not responding. Last check: 2007-10-31)
		I would rate unsharp masking as one of the top three most painful things to do in the darkroom.
		The mask is essentially a thin positive added to the negative.
		An added benefit is that the unsharp nature of the positive creates a tiny halo around the negative and therefore the apparent sharpness of the image is greatly enhanced.
	www.ilford.com /html/us_english/ILFOPRO/forum/topic.asp?TOPIC_ID=6301 (1822 words)

	UnSharp Masking or Refocusing the Scan
		UnSharp Masking refocuses the scan by adjusting the contrast of edge detail.
		As the DPI increases, so must the UnSharp Masking Radius.
		Settings that work for Me The UnSharp Masking settings listed here are offered as a place to start.
	home.att.net /~cthames/Unsharp1.htm (511 words)

	Contrast Masking Kits, ordering information
		A manual including complete instructions on various techniques, including mask making and use, including the original articles on SCIM (shadow contrast increase mask), CRM (contrast reduction mask, shadow mask, or "unsharp mask"), and HLM (highlight mask) by Dennis McNutt and Mark Jilg, with complete instructions on making a pin-registration negative carrier for your enlarger.
		The pins can be used for all paper-plane masking techniques, or they can be taped to a light table for use in other masking work, such as dodge/burn masks.
		The Contrast Masking Kit is available for $79.95 plus shipping and can be shipped almost anywhere in the world.
	www.maskingkits.com /ordering.htm (875 words)

	Digital darkroom - Composites by examples (Site not responding. Last check: 2007-10-31)
		It requests to create an unsharp mask by using a gaussian filter (low-pass) according a threshold to experiment.
		Both images were postprocessed with unsharp masking to enhance features in bright and dim area.
		Trying to improve your small scales details using an unsharp mask, you amplify in the same time the noise hidden in these high frequencies.
	www.astrosurf.com /lombry/digital-darkroom-examples2.htm (1086 words)

	Sharpening
		The unsharp mask filter places a dark halo at the edge of the darker of two image elements and a lighter halo at the edge of the lighter element.
		The selection of radius, strength, and threshold parameters to be used for unsharp masking before display or printing is largely a trial-and-error process and image editors provides a slightly different variation of them for the user to adjust.
		Threshold controls where the unsharp masking effect will be applied.
	fhctech.org /fhc/classes/sharpening.htm (316 words)

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