Easy-to-follow video tutorials help you learn software, creative, and business skills.Become a member

Using Gaussian luminance distribution

From: Photoshop CS3 Sharpening Images

Video: Using Gaussian luminance distribution

So those of you who watched the previous exercise and are sitting there going, I knew was not going to learn anything from that, what in the world? I mean, now I know that you can't drop below 0.3 pixel and get in the effect out of Gaussian Blur. Who cares? But yet you still are watching me. In case you fall in to that demographic, let me assure you its still highly theoretical information, but it goes to the to the heart of how Photoshop works. I cannot stress this enough. Back in the old days programs with blur images, this was before Photoshop, they would blur images by assigning a linear blur and then Photoshop came around and offered the Gaussian Blur and it made all the difference in the world.

Using Gaussian luminance distribution

So those of you who watched the previous exercise and are sitting there going, I knew was not going to learn anything from that, what in the world? I mean, now I know that you can't drop below 0.3 pixel and get in the effect out of Gaussian Blur. Who cares? But yet you still are watching me. In case you fall in to that demographic, let me assure you its still highly theoretical information, but it goes to the to the heart of how Photoshop works. I cannot stress this enough. Back in the old days programs with blur images, this was before Photoshop, they would blur images by assigning a linear blur and then Photoshop came around and offered the Gaussian Blur and it made all the difference in the world.

I know that's hard to believe, but let me show you, what's up here. As I say its very important to understand this whole Gaussian luminance distribution curve in order to understand whats going on with sharpening inside of Photoshop. So here I am working inside image called Gaussian demo.PSD found inside the 03 sharpen filters folder. I'm going to go over to the Layers palette, just to confirm that I've the Background layer selected. So we have got the rectangular area black in the left, a rectangular area of white on right. How is that for narrating the obvious? Lets go ahead and hide the Layers palette for a moment.

I'm going to go up to the Filter menu and I'm going to choose Blur and I'm going to choose Box Blur. A Box Blur even though it was only added like a few years back inside a Photoshop its an old school blurring tool. This is the way other programs used to work back in the old days. It assigns a linear blur, so I'm going to go ahead and choose the command. And I'm going to take the Radius value- you notice that it looks just like the Gaussian Blur dialog box- I am going to take the Radius value up to a 140 pixels, so something really large and the idea- by the way, this image measures 800 pixels wide.

So we are going to consume an area of about 280 pixels in the center here because Radius value times two gets you to the diameter. So about 280 pixels worth of drop off in the middle of this image and I'll go ahead and click OK. So its a zip we have converted what used to be a black and white image into a black and white gradient. Now with the slope right here in the center portion of the image. So I'm going to bring up the Layers palette, I hope this make sense. I have got a couple of graphs going on, all these other layers are graphs.

So I'magine that we are to graph the image and anywhere where the image is black, we would graph those pixels to the bottom of the image and anywhere where the image is white we'd graph it to the top and then any gray values in between would be graphed in between as well. So let me show you what I'm talking about. I'll turn on original and this original version of this image. So if I go ahead and undo the modification, black over here on the left, white over here on the right, so I'll press Crtl+ Z or Command + Z again to redo that Box Blur that I've applied, so here's my graph.

So all these pixels used to be black, hence this horizontal line along the bottom of the image, all these pixels used to white, hence this line across top of the image and there is our drop off in between. So it's a cliff essentially between those two extremes. That's the way the image used to be. I'll go ahead and turn that off and I'll turn on Linear slope, this is the way it is now. So just these pixels over here are black. These pixels over here are white. And I can confirm that by the way by getting my Magic Wand Tool. I'm going to go and switch over to the Magic Wand, make sure tolerance is set to zero, anti-alias is off.

These are not default settings by the way, so you would have to change them if you are following along. Contiguous is turned on, Sample All Layers is turned off, so settings as you see them. Background layer is selected. I'll click right there and you can see that those are the black pixels. So sure enough, my graph is accurate and these guys over here are the white pixels and in between the white pixels and, Shift-click over here, the black pixels, it's the area of grey pixels that has the linear drop off, notice that. There is a very clear point at which the gradient begins and the gradient ends.

So I'll go ahead in back step to get rid of those selection outlines. And the reason that this is important to know the fact that we have this point of which the gradient begins ands ends here is because, I'll go ahead and turn off the Linear slope, that means that we have a harsh transition at the point at which the blur begins at the point and the point at which the blur ends. So this is not a good blur. If we were to use this blur as a drop shadow for example, we would get a very sharp transition at edge, at the outer edge of the drop shadow, which would defeat the purpose since the drop shadow's supposed to look soft and it would no longer look soft, it would look sharp thanks to that linear distribution.

Lets go ahead and undo the Box Blur. And the solution is Gaussian Blur. I'm going to go up to the Filter menu with the Background layer still selected, go to Blur and I'll go ahead and choose Gaussian Blur and I'm going to apply that same value, 140 pixels. Now notice something right off the bat, I think you can see this, as I was saying this is an 800 pixel wide image and yet just about the entirety, with just a few edge pixels intact, is taken up with this blur. Even though if you multiply a 140x2, you still get 280 and yet we are taking up the entire 800 pixels, almost just a few pixels on the side left over. And that's the function of the spreading that is occurring thanks to Gaussian Blur, the Gaussian distributions.

I'll go ahead and click OK to accept that modification and you can now see that we have a much softer effect and that the colors are distributed not like this any more, not like the Linear slope, they are now distributed like this. We now have a Gaussian slope and notice what happens is that the colors transition very slowly at the beginning, more rapidly in the middle and very slowly at the end one again. If you want to confirm that, go ahead and bring up the Color palette and you can see that my foreground color is currently a 100% black.

I'm going to grab my eyedropper and if I click over here on the far left side of the image, watch this value right there, watch that 100% value, what is currently 100%. If I click and hold on far left side of the image, its still says the100%, but as I move, I'm moving my mouse very slowly, notice that there is 99 and there, pretty soon, we'll see 98, then well see 97, 96, 95, things are going more and more rapidly and now notice its going very rapidly. We have a very rapid transition between these colors and now notice it's dropping off very, very slowly again and I'm still dragging my cursor over to the right and then finally we go from one to zero.

So very slow transitions, that is at the edges, and the reason for that is because you want to have a gradual drop off so that your drop shadow, once again, just by way of example, doesn't look like it has a crisp, clear edge to it, instead it appears to just gently fade away. That gives you much more naturalistic effect and much more organic effect and that is like what I'm calling the Gaussian luminance distribution is so very important to the realism to the credibility of images that you produce with Photoshop.

Alright. So I'm going go ahead and hide that Color palette and just in case this graph isn't totally doing it for you, maybe this version will. This is my Gaussian black and white version of the graph. So basically the white is very slowly growing to take up what used to be black space. Another way, I don't know if that helps. Just another way of viewing the image, and probably the best one is this guy that I came with here. So there is the Gaussian slope with the Gaussian Blur in the background. In the next exercise, we are going to look at Unsharp Mask and then after that I'm going to show you how you can make Unsharp Mask all by yourself, if you feeling like a boy or girl scout, you can make Unsharp Mask using Gaussian Blur and nothing more.

Show transcript

This video is part of

Image for Photoshop CS3 Sharpening Images
Photoshop CS3 Sharpening Images

115 video lessons · 17011 viewers

Deke McClelland
Author

 
Expand all | Collapse all
  1. 50m 30s
    1. Why every image needs sharpening
      2m 38s
    2. Understanding the effects of sharpening
      5m 26s
    3. Understanding the mechanics of sharpening
      4m 19s
    4. Understanding sharpening and gradual transitions
      3m 21s
    5. Understanding sharpening and noise reduction
      4m 0s
    6. Understanding amount and radius
      7m 50s
    7. Measuring your screen resolution
      6m 19s
    8. Using reliable zoom ratios
      5m 30s
    9. Calculating the actual print size
      4m 54s
    10. Gauging the ideal sharpening settings
      6m 13s
  2. 59m 31s
    1. Everyone knows you sharpen last (and everyone is wrong)
      1m 8s
    2. Understanding the conventional sharpening workflow
      5m 4s
    3. Flattening and saving to TIFF
      6m 39s
    4. Downsampling (and why you shouldn't upsample)
      6m 8s
    5. Understanding last-step sharpening
      6m 44s
    6. Recognizing problems with the conventional workflow
      9m 38s
    7. Erasing sharpening with the history brush
      4m 30s
    8. Using alternative sharpening workflows
      2m 37s
    9. Sharpening a scanned photograph shot on film
      2m 45s
    10. Sharpening a digital photograph
      3m 6s
    11. Sharpening specific details
      3m 43s
    12. Finding broad workflow conclusions
      2m 49s
    13. Learning that technique trumps timing
      4m 40s
  3. 1h 27m
    1. Comparing and contrasting neighboring pixels
      1m 6s
    2. Using the Gaussian Blur filter
      4m 25s
    3. Using Gaussian luminance distribution
      4m 47s
    4. Using the Unsharp Mask filter
      4m 54s
    5. Understanding the history of Unsharp Mask
      3m 51s
    6. Building your own USM with Gaussian Blur
      7m 35s
    7. Using the Smart Sharpen filter
      7m 35s
    8. Compensating for camera shake
      8m 50s
    9. Building your own Smart Sharpen with Lens Blur
      6m 59s
    10. Using directional sharpening with Emboss
      9m 13s
    11. Using Smart Sharpen extras
      8m 56s
    12. Using Convolution Kernels for more accuracy
      7m 8s
    13. Using the High Pass filter
      7m 32s
    14. Using Luminance Sharpening
      5m 5s
  4. 2h 14m
    1. Smoothing filters, smart objects, and masks
      1m 25s
    2. Using the Median filter and Dust and Scratches
      7m 7s
    3. Using Smart Blur and Surface Blur
      6m 12s
    4. Using the Despeckle filter
      8m 17s
    5. Softening flesh tones selectively
      10m 15s
    6. Using the Reduce Noise filter
      7m 27s
    7. Combining smoothing and sharpening
      8m 24s
    8. Making an image into a smart object
      9m 24s
    9. Applying editable smart filters
      6m 8s
    10. Combining two smart filters
      8m 5s
    11. Assigning a filter mask
      5m 59s
    12. Nesting one smart object inside another
      10m 32s
    13. Employing a static High Pass layer
      8m 59s
    14. Matching static pixel-level edits
      4m 37s
    15. Avoiding clipping with luminance blending
      9m 7s
    16. Sharpening and smoothing
      6m 36s
    17. Making an edge mask
      8m 14s
    18. Making a non-edge mask
      7m 17s
  5. 1h 33m
    1. Sharpening with Adobe Camera Raw
      1m 29s
    2. Introducing Camera Raw (4.1 or later)
      8m 13s
    3. Understanding why to sharpen for source
      5m 14s
    4. Using Camera Raw’s sharpening control
      5m 52s
    5. Previewing limitations and tricks
      6m 45s
    6. Why downsampling doesn’t work
      3m 12s
    7. Reducing chromatic aberration
      7m 30s
    8. Using the Defringe option
      3m 32s
    9. Understanding high frequency, low radius
      5m 21s
    10. Raising the Detail value
      3m 6s
    11. Using on-the-fly edge masking
      5m 41s
    12. Sharpening a low-frequency portrait
      6m 36s
    13. Eliminating color noise
      4m 47s
    14. Reducing luminance noise
      4m 42s
    15. Correcting “false sharpening”
      7m 15s
    16. Reducing shadow noise
      5m 22s
    17. Approximating ACR sharpening in Photoshop
      8m 35s
  6. 59m 8s
    1. Gauging and exploiting luminance frequency
      1m 27s
    2. Using low-frequency source sharpening
      5m 53s
    3. Using High Pass for portraits
      4m 19s
    4. Actioning a low-frequency edge mask
      7m 42s
    5. Modifying the source sharpening
      5m 21s
    6. Using high-frequency source sharpening
      5m 26s
    7. Using Smart Sharpen for cityscapes
      3m 2s
    8. Actioning a high-frequency edge mask
      5m 4s
    9. Downplaying color artifacts and clipping
      4m 4s
    10. Sharpening a medium-frequency image
      5m 24s
    11. Sharpening a layered composition
      7m 16s
    12. Sharpening for multiple frequencies
      4m 10s
  7. 1h 8m
    1. Who needs dull when you have sharp?
      56s
    2. Focusing in on a person’s eyes
      4m 22s
    3. Blurring the area outside the eyes
      4m 22s
    4. Sharpening eyes and other details
      5m 38s
    5. Darkening the lashes and eyebrows
      7m 13s
    6. Sharpening dark-haired people
      5m 2s
    7. Edge mask and emphasize
      3m 39s
    8. Nesting a Smart Sharpen effect
      4m 48s
    9. Density mask sharpening
      5m 35s
    10. Adding depth of field
      4m 39s
    11. Sharpening a background
      4m 23s
    12. Masking background from foreground
      8m 51s
    13. Eliminating halos around a person
      5m 38s
    14. Deepening and warming a background
      3m 28s
  8. 1h 18m
    1. Reverting back to convention
      1m 37s
    2. Understanding the use-neutral composition
      4m 15s
    3. Restoring much-needed antialiasing
      4m 2s
    4. Reducing noise in a high-frequency image
      7m 24s
    5. Making a third-level smart object
      3m 55s
    6. Preparing an image for print
      5m 18s
    7. Using ideal settings for commercial reproduction
      5m 37s
    8. Calculating very large-format settings
      5m 11s
    9. Using ideal settings for inkjet output
      4m 26s
    10. Sharpening for commercial reproduction
      5m 45s
    11. Sharpening for inkjet output
      4m 58s
    12. Revealing high-frequency multipass sharpening
      5m 21s
    13. Using Gaussian Blur to sharpen hair
      5m 41s
    14. Flatten, Save As, Resample, and Sharpen
      5m 9s
    15. Revealing low-frequency multipass sharpening
      3m 30s
    16. Sharpening an image for web or screen
      6m 22s
  9. 1m 50s
    1. Goodbye
      1m 50s

Start learning today

Get unlimited access to all courses for just $25/month.

Become a member
Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Join now "Already a member? Log in

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed Photoshop CS3 Sharpening Images.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Your file was successfully uploaded.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.