12 Replies Latest reply: Jun 18, 2013 9:46 AM by CorkyO2
HPL1955 Level 1 Level 1 (0 points)

What is the difference between "definition" and "sharpening"?


MAC pro
  • 1. Re: "definition" vs. "sharpening"?
    léonie Level 9 Level 9 (51,640 points)

    The definition enhancement or definition quick brush will add clarity to the image by removing layers of haze. This will make colors more saturated and increase the contrast a little.

    see for example: Working with the Definition Quick Brush Controls

     

    The sharpening adjustment will emphasize the edges by mitigating the effects of smoothing or blurring. The image will appear sharper, but the noise may increase .

    See:  Working with the Sharpen and Edge Sharpen Controls

     

    So use "definition" adjustments to make hazy pictures more brilliant, and (edge) sharpening to reduce blurriness.

     

    Regards

    Léonie

  • 2. Re: "definition" vs. "sharpening"?
    Frank Caggiano Level 7 Level 7 (23,795 points)

    Contrast, definition and sharpening all deal with contrast. It's where on the image that the contrast is being manipulated that changes.

     

    Contrast works on the entire image, definition works on a more local level and sharpening (edge sharpening that is, the sharpening you should use in Aperture 3) works on edges within the image.

     

    So if the image is overall flat then try the contrast adjustment. If there are areas that are flat but overall the image is ok try definition. And edge sharpening can give an other wise OK image a little extra pop.

     

    Remember whenever you increase contrast you will also increase noise so use the adjustments sparingly.

     

    regards

  • 3. Re: "definition" vs. "sharpening"?
    HPL1955 Level 1 Level 1 (0 points)

    I am using Ap 2.  There are two areas where there is a sharpen tool (RAW fine tuning, and down at the bottom).  How do they compare to the sharpen tools in PS?

     

    Thanks

  • 4. Re: "definition" vs. "sharpening"?
    Kirby Krieger Level 6 Level 6 (11,915 points)

    Sharpening digital camera images is a complex topic.  I suggest starting with this short primer:

     

    http://www.cambridgeincolour.com/tutorials/image-sharpening.htm

     

    The sharpening in the RAW Fine Tuning adjustment is, procedurally, "capture sharpening".  The other sharpening tools in Aperture are used for "aesthetic sharpening" (a/k/a "artistic sharpening", a/k/a "creative sharpening") and "output sharpening".  Aesthetic sharpening is whatever you want it to be.  Output sharpening should be device-dependent: sharpening for a JPG destined for the Web will be different from sharpening done to a TIFF being sent to a printer.

     

    (Added:)

    I don't swear to the exactitude of the following, but fwiw, I think of capture sharpening as what needs to be done to prepare a digital negative for editing; I use aesthetic sharpening to guide the eye of the viewer; and I apply whatever output sharpening is advised in order to _retain_ the look of the edited Image when I publish it as a digital file.

     

    Message was edited by: Kirby Krieger

  • 5. Re: "definition" vs. "sharpening"?
    Kirby Krieger Level 6 Level 6 (11,915 points)

    Frank -- can you expand on this a little (or point me in the right direction)? 

    Frank Caggiano wrote:

     

    Contrast, definition and sharpening all deal with contrast. It's where on the image that the contrast is being manipulated that changes.

     

    Contrast works on the entire image, definition works on a more local level and sharpening (edge sharpening that is, the sharpening you should use in Aperture 3) works on edges within the image.

    Is contrast no more than a luminance remapping applied uniformly to each pixel based on its luminance but independent of its neighbors (in essence, displacing all luminance values away from the middle)?  And then edge sharpening is not just luminance but also hue, and very dependent on its neighbors.  And definition is ... where I get lost.

     

    Thanks.

  • 6. Re: "definition" vs. "sharpening"?
    léonie Level 9 Level 9 (51,640 points)

    Contrast, definition and sharpening all deal with contrast. It's where on the image that the contrast is being manipulated that changes.

     

    That will depend on your definition of contrast, Frank ; your usage of this term is more general or all-embracing then the way I like to use it. I use the term "contrast" to describe the local or global difference in intensity or color, and would reserve "contrast change" for adjustments, that are intended to (and will) spread or lower this difference - locally or globally. Viewed this way, many adjustments, that are intensity remappings, are only accidentally contrast adjustments and I would not lump them into this category.

     

    • I.e. "Definition" does an intensity remapping, but it is mainly shifting the intensities by subtracting locally an equal amount of "whiteness". This will make the colours more vibrant but preserve the local contrast. By Apple's own description in the manual:

    You use the Definition Quick Brush adjustment to add clarity and reduce haze without adding too much contrast to the area of the image the adjustment is brushed on.

    • Sharpening will locally increase the steepness (gradient) of edges - the rate at which the intensity will vary from light to dark, but the overall contrasts should locally remain the same.  frequency based sharpen filters will even decrease the global contrast.

    For example, if you have a blurred image with a dark object on a light background, the edge may extend over 5 pixels width because of the blur, and vary slowly from dark to light. After sharpening the edge will be narrower and thus steeper, and maybe only extend over two or thee pixels width. But it will still only have the same local contrast between dark and light areas.

    Only if you are overdoing on the intensity of sharpening, you may notice and additional contrast increase along the edge: The dark side of the edge may become darker and the bright side brighter, to allow the edge to become even steeper. The edge will be surrounded by darker and lighter lines.

     

    As a follow up I'll try to post a few examples, to explain hat I mean, if Jive will let me

  • 7. Re: "definition" vs. "sharpening"?
    léonie Level 9 Level 9 (51,640 points)

    Example 1:

    Four image versions - left to right - original, definition enhancement, sharpening quick brush, contrast.

    Screen Shot 2013-06-18 at 10.29.34.PNG

    Cropped versions: - left to right - original, definition enhancement, sharpening quick brush, contrast.

     

    Screen Shot 2013-06-18 at 10.25.19.PNG

     

    Difference images: the original subtracted from the adjusted version:

    left to right - definition enhancement, sharpening quick brush, contrast.

    Screen Shot 2013-06-18 at 13.05.05.PNG

    You may notice, how the "Definition" enhancement (left) mainly intensifies the hue; the grass will become greener,  the white stripes brown or blue.

    Sharpening is mainly adjusting the luminance, and "Contrast" will may shift the colors.

     

    A close-up of the Difference picture of the sharpened Zebra stripes: The edges are outlined by dark and light (meaning subtracted and added values).

    Screen Shot 2013-06-18 at 13.08.12.PNGScreen Shot 2013-06-18 at 13.10.28.PNG

  • 8. Re: "definition" vs. "sharpening"?
    Kirby Krieger Level 6 Level 6 (11,915 points)

    I'm trying to follow along ... .  For me to do so, I think I need definitions of "intensity" and "color" and "whiteness".  Of course, example will help (and shame on Jive!).  (I realize, too, that I am partially asking for free tutoring.  Are these lessons already available on the Web?)

     

    Fwiw, I was taught (and teach) from among the many children of the Munsell system, where "color" is rigorously and exactly defined by three parameters equal to hue, saturation/chroma, and intensity/brightness/luminance/value, where:

    • hue = where on the spectrum of visible light
    • saturation/chroma = how far removed from a neutral gray of the same luminance (where on a vector from gray to "fully saturated"), and
    • intensity/brightness/luminance/value = the degree of lightness (where on a segment from darkest dark to lightest light).

     

    If this rationalization of vision is no longer useful, let me know.

  • 9. Re: "definition" vs. "sharpening"?
    léonie Level 9 Level 9 (51,640 points)
    If this rationalization of vision is no longer useful, let me know.

     

    The  system is perfect, and I am using it too, when  referring to the perceived properties of a color with respect to the visual system or in a program GUI, when when we are dealing with color.   The human visual system, however, is only one kind of sensor.

     

    In my post above I was referring to algorithms that are modifying the pixels of a digital image, and these algorithms are based on the physical definition of intensity, in one of the many systems suitable for the type of the sensor used. 

    With "Intensity" I was referring to values of any channel of a digital image function, independent of the underlying radiometric system (http://en.wikipedia.org/wiki/Radiometry).

     

    O.K. I'll try a different approach on describing what "Definition" adjustment (probably) does.

    Apple does not reveal much, how "Definition" adjustment is working:

    You use the Definition Quick Brush adjustment to add clarity and reduce haze without adding too much contrast to the area of the image the adjustment is brushed on.

    This short sentence suggests, that the "Definition" adjustment is using well known image restauration algorithms (from remote sensing) for Atmospheric Correction.

     

    The objective is, to enhance the image to a state what it should look like, if there were no haze.

     

    Imagine, you would take a picture with your camera in a perfect vacuum (hold your breath).

    In the vacuum, the resulting image would solely depend on the properties of your camera, on the lightsources,  the irradiance functions of the surfaces of the objects in the scene and the relative positions of objects, lightsources, camera.

    If there were fog, haze, etc., this will change the recorded irradiance at the sensor of the camera.

    • The light from the light sources will be attanuated by the haze (scattering, absorption), so the irradiance at the surface of the objects will be different and the reflected light will be different.
    • The fog, haze, ... will scatter light directly into the lens of the camera - so the camera sensor will record a mixture of light scattered from the haze plus light reflected from the object in the scene, and this mixture "additive" - the irradiance you want, plus the irradiance from the haze.

     

    What haze reduction does: It estimates the amount of the irradiance at the camera's sensor that results from scattering by the haze and subtracts it from the total irradiance.

    Let's talk about "whiteness" - it's aka of saturation, but not the same. Basic haze correction assumes, the scattering of light to be non-selective, meaning it will not depend on the wave length of the light (true for large, white scattering particles). So it should have the color of the light emitted by the light sources - in daylight "white", as defined by the white white balance. The result will be an image with less saturated colours, and subtracting the added white will restore the missing saturation.

    The big problem is to estimate the amount of added "white", if you only have the image to go on and no further data about the recording situation.

    Apple does not reveal how they are doing it.

    Screen Shot 2013-06-18 at 16.06.06.PNG

    Example (from Sabins-Jr., F. F. (2000). Remote Sensing Principles and Interpretation. Freeman and Company, New York, 3 edition.):

    The Brightness profile shows the image brightness (intensity) along a scanline and the effect of scattered light adding to the brightness.

  • 10. Re: "definition" vs. "sharpening"?
    Frank Caggiano Level 7 Level 7 (23,795 points)

    I'll not attempt top wade through Léonie's and your scholarly discourse right now but do what to address this:

     

    And definition is ... where I get lost.

     

    I'm assuming it was my reference to locally applied that lost you.  To my eye when I use the definition adjustment  as opposed to the contrast adjustment the adjustment seems to be more locally applied, as opposed to contrast that seems to apply the adjustment to the entire image.

     

    BTW looking through APTS, Scoppettuolo  says basically the same thing when it comes to contrast and definition.

     

    regards

  • 11. Re: "definition" vs. "sharpening"?
    Frank Caggiano Level 7 Level 7 (23,795 points)

    HPL1955 wrote:

     

    I am using Ap 2.  There are two areas where there is a sharpen tool (RAW fine tuning, and down at the bottom).  How do they compare to the sharpen tools in PS?

     

    Thanks

    Sorry, don;t use PS so I can;t address. I'm sure there is someone her who does use PS and could address this.

     

    As for still using Aperture 2. you don;t mention what version of the OS you are running but  if you could you should think about upgrading to 3. There have been some major changes to the program, all for the better in my opinion.

     

    regards

  • 12. Re: "definition" vs. "sharpening"?
    CorkyO2 Level 4 Level 4 (1,290 points)

    HPL1955 wrote:

     

    I am using Ap 2.  There are two areas where there is a sharpen tool (RAW fine tuning, and down at the bottom).  How do they compare to the sharpen tools in PS?

     

    Thanks

    In Aperture 2, the following is a decent comparison:

     

    1 - RAW fine tuning is similar to what you would do with Adobe Camera RAW sharpening section (where you try to mitigate any softness from the camera's processing of the sensor data). This is typically referred to as 'capture sharpening'.

     

    2 - The sharpen function in Aperture 2 is basically like the PS Unsharp Mask (Filter menu > Sharpen > Unsharp Mask in full version of PS). This affects the whole image and doesn't really do detailed edge finding when applied.

     

    Note - Aperture 3 has the new 'Edge Sharpen' tool which does a better job of finding the edges and then applying sharpening in progressive steps (where the sharpening application falls-off to prevent artifacts). This adjustment can be applied either globally or locally with a brush in Aperture 3.

     

    If you are sticking with AP 2 and have PS, you can do a similar effect in PS full version by doing an 'Edge Find' command on a mask and inverting before running the Unsharp Mask function. There are a number of articles detailing this procedure if you Google for sharpening techniques in PS (more involved than I would like to comment on in the Aperture forum).

     

    Hope that helps.