dSLR sharpness experimentation - DPChallenge Forums

Sigma 24-70mm f/2.8 EX Aspherical DF for Canon

07/19/2005 11:52:24 PM · #1

Shot the following image today under gray, hazy light at Provincetown. 300D Canon, camera sharpening turned off. WB was set out cloudy, which was a mistake; the light was warmer than that, so the image is a little warm. But that's neither here nor there for what I am doing, which is checking out sharpness calculations.

The first shot is straight from the cam. Second shot rotated for horizon and cropped off top (planned in shooting) to a more normal aspect ratio. Sharpening (USM) was applied to entire image. I also added a gradient to the sky just for the hell of it. Third shot is nothing more than a crop of second shot. All were resized to 640 pixels and saved for web at 150 kb.

Here's the interesting thing to me: before resizing and saving for the web, the tightly cropped version, when enlarged to fill the screen, seems MUCH sharper than the relatively full-frame, sharpened version, when IT is sized to fill the screen (vertically in each case). In other words, on this image, as you zoom in, it appears to get sharper and sharper, up to a point.

It's an eye-opening illustration to me of just how much sharpening is output-dependent; that is, the larger I plan to make the print the LESS I need to sharpen it to get the same visual effect. I think.... In any case, these images clearly show the need for post-production sharpening when using the dSLR. I think...

Robt.

hdogg4u

Canon EOS-20D

07/19/2005 11:58:23 PM · #2

I know what your doing Robert. Your testing out the limits of the camera before your 20D arrives. This way you can be a jump on things already. I see here in the future mastering your camera up to a point where you'll be raking in the ribbons. Well congrats to you on moving in the DSLR and I hope you do win a lot a of ribbons. You taught us all very much.

Discraft

Canon EOS-20D

Sigma 18-50mm f/2.8 EX DC for Canon

07/19/2005 11:58:32 PM · #3

the cropped versions really look much more sharper.
So can you tell us what method you used to unsharp and maybe the values of the use of the sharpness.

aboutimage

Canon EOS-30D

Canon EF 70-200mm f/2.8L IS USM

07/19/2005 11:59:32 PM · #4

An interesting observation, Robert. I just picked up the PhotoKit Sharpener. It seems to focus on the same issue: that sharpening is output-dependent. In fact, it does its sharpening in 3 stages: input-dependent, creative, and output-dependent. Great tool, and interestingly set-up: it's not a filter. It's an automation tool. Creates sharpening layers, so you can fade the opacity if it's overdone.

brianlh

Canon EOS-450D Rebel XSi

Canon EF 24-70mm f/2.8L USM

07/20/2005 12:18:52 AM · #5

I think your conclusions are accurate - it certainly agrees well with the point of view that any image reduced in size should be sharpened again before finishing. What settings did you choose to go with for USM? I've been using an action that I got from a link that librodo provided DPC with. I turned all the options dialogs on though so that I can adjust as needed. It defaults to 18/40/0, 150/0.3/0, Fade USM @ 100, 150/0.3/0, Fade USM @ 100 again. It generally works well, though I sometimes reduce the radius on the first if the contrast is too much and reduce the amount on the second two if the noise is too much.

Sigma 18-50mm f/2.8 EX DC for Canon

07/20/2005 12:22:51 AM · #6

Originally posted by Discraft:

the cropped versions really look much more sharper.
So can you tell us what method you used to unsharp and maybe the values of the use of the sharpness.

For these I used the action Manny provided, the one brian referred to. It's very effective. Brian, now do you set it so "options dialogues" are on? I don't have much experience creating actions.

Aboutimage, I'm checking out the Photokit sharpener also. I downloaded the demo, am still not sure just how to use it effectively. Haven't studied it.

Robt.

Discraft

Canon EOS-20D

07/20/2005 12:26:56 AM · #7

where can i get that action?

brianlh

Canon EOS-450D Rebel XSi

Canon EF 24-70mm f/2.8L USM

07/20/2005 12:51:59 AM · #8

Frederico: here is manny's picture on trekearth

scroll down to Luko's comment and then click on workshop. Read the details in the comments about sharpening. I didn't find the downloadable action, but I just recorded it myself.

Robert: Just click the little boxes next to the action (or next to each individual step, if you like) until the box shows up (not the check mark, but the thing to the right of it) - this will enable you to choose the options in the dialog boxes that normally come up. I left the Fade steps disabled because I saw no need to toy with those.

Prof_Fate

07/20/2005 01:11:30 AM · #9

Sharpening is very dependent on scene, camera used, and file size (i sharpen a 640x400 differently than the 3000x2000 version).

As for printing...since i do 98% of my work for screen display, I know that end of it.

I need an idea of what to do for 4x6 or 5x7 or 8x10 prints. harder when you use a lab to get immediate feedback, and costlier too!

Neil

Fujifilm X-T30

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

07/20/2005 01:43:53 AM · #10

Originally posted by brianlh:

What does "Fade USM @ 100" do? Doesn't that actually do nothing with a 100 setting? Is it just to get fade USM into the history buffer for backtracking and adjusting?

brianlh

Canon EOS-450D Rebel XSi

Canon EF 24-70mm f/2.8L USM

07/20/2005 01:45:46 AM · #11

I'm really not sure, sorry :( - I just copied what it mentioned on the comments. I am pretty sure that it does something though, as I sometimes (though usually not) see noticeable changes in appearance between the Fade option and its preceding USM.

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

07/20/2005 02:17:47 AM · #12

Originally posted by nshapiro:

Originally posted by brianlh:
I think your conclusions are accurate - it certainly agrees well with the point of view that any image reduced in size should be sharpened again before finishing. What settings did you choose to go with for USM? I've been using an action that I got from a link that librodo provided DPC with. I turned all the options dialogs on though so that I can adjust as needed. It defaults to 18/40/0, 150/0.3/0, Fade USM @ 100, 150/0.3/0, Fade USM @ 100 again. It generally works well, though I sometimes reduce the radius on the first if the contrast is too much and reduce the amount on the second two if the noise is too much.

What does "Fade USM @ 100" do? Doesn't that actually do nothing with a 100 setting? Is it just to get fade USM into the history buffer for backtracking and adjusting?

Partly, but also I think it may be working on other-than-normal layer mode on the fade.

R.

Message edited by author 2005-07-20 02:18:57.

Neil

Fujifilm X-T30

07/20/2005 09:07:10 AM · #13

My guess is that you are getting more sharpening on the crops because there's more detail--more, and larger, edges to contrast.

The sharpening action appears to work well. Yet, it seems to be designed inconsistently with the proper workflow, or at least it's at odds with what I've learned about sharpening over the past year or two.

The most dramatic improvement in this action comes from the first USM step. The first USM in the action is actually not a sharpen, but a technique called "Local Contrast Enhancement". This is typically something you want to do before reducing, whereas sharpening is something you want to do after reducing a photo, or in steps during a reduction. Here's a link to one good explanation/tutorial on it, for those interested: Local Contrast Enhancement. I can't find a written source right now for the incremental argument. I learned about that a year or two ago from Marc Guggenheim when I was a member over at Photopoints. In that case, the idea is that you do sharpening and LCE in stages, as you reduce the image progressively. The LCE is his words is basically a preparation for the reduction.

So for those who have been using this action for a while, if there's anyone, or those experimenting, I'm curious. I found the results worked well if I sharpened before I reduced, but not so well if I applied it after. I even split the action, and used my own LCE before the reduction, and then the rest afterwards. In both cases, I found the USM too extreme on the reduced file.

Anyway, I just wanted to add this info to this interesting sharpening discussion. As a side note, Robert (and others), if you haven't already, you might want to also look into some of the excellent sharpening actions (I'll post links as I find them):

10D Finisher is very good (actually, while looking for the link, I found in my bookmarks a page which shows examples of a number of sharpeners and has links... (Sharpeners)

Canon EF 70-200mm f/2.8L IS USM

07/20/2005 10:50:32 AM · #14

I applied the action to the full-size shot in this case, and yes this is what it's intended for. I HAVE used it after reducing size, in the past, but on a separate layer and then faded to achieve less-extreme results. I have a lot to learn here.

Robt.

holdingtime

Canon EOS-5D

07/20/2005 11:01:23 AM · #15

I know I do when it comes to Photo shop and prepairing prints for here. I seem to get a lot of comment that a pic might be soft when I know the original is tack sharp and clear. I need lots of help with prossesing end of things.