After-Before Friday Forum – Week 66…

I don’t normally pick up random stuff to photograph at home but when I saw this tiny snail shell I really wanted to photograph it with my super macro lens.  That lens is touchy, focus-wise, and requires being on a tripod with a focusing rail, so I’ve only taken photos with it in the ‘studio’.  It felt weird to bring home this ‘dead’ snail, but I tried to convince myself that it was like bringing home a seashell.  Anyway, this After image is 15 photos focus-stacked, then the color is fixed and the sharpness improved.  The snail shell itself is only 1/2 inch (1.27 cm) diameter!

Go find out what everyone else did this week for AB Friday Forum here.

I have joined ABFriday (after before Friday), it is a forum hosted by Ben at Aperture64. This week’s forum can be seen here.

Every Friday Ben showcases after/before photos we’ve submitted. Then, if we choose, we can tell how we did it on our own blogs.


At first glance, I didn’t do anything different to this image that I haven’t talked about before.  I created one image from 15 photos by focus-stacking, I lightened and darkened some areas,  I played around with Local Normalization and Luminosity Masks, and I added some sharpness with a Wavelet Decompose Filter.  The reason I decided to submit this image into the After-Before Friday Forum is because of how I changed the color cast (or white balance) with the use of Color Curves.  That is what I will concentrate on for this tutorial, go check out the links for info on the other steps. 🙂


Let me tell you about the photo shoot setup… My living room gets morning light that spills through my sliding glass door (camera right), I put the snail shell on a white board, then I placed another white board on its side to create fill light (camera left).  Then I set up my camera on a tripod with a focusing rail.  I used a remote for the shutter button, and I had the camera’s mirror locked to reduce camera shake.  Once I created an image that I was pleased with (Before shot), I then moved the focus to the front edge of the snail shell, then slowly I took photos as I incrementally moved the focus across the snail (I marked the beginning and end of this set with a photo of my hand).  In the end I had 15 images with different sections in focus (actually 16 if you count the Before shot, which wasn’t actually used in the stacking… it is my “if I was ONLY going to take one photo” shot).

Let’s go ahead and look at my layers…layers--gimp

  1. First, I took 15 images and focus-stacked them using software I talked about in this post.  Then I cleaned up the image created from the stack in GIMP1, as explained in this post.
  2. Next, I played with color curves… I’m going to concentrate on the tutorial here.  I told you about the photo shoot setup so that you would understand some of the choices I made during this step.  Because the snail shell was on a white board I knew that the color was way too yellow.  Originally I thought I would just adjust the blue/yellow in color curves. But it just didn’t look right.  Then I remembered this tutorial from Pat David, where he altered the color of a portrait based on another image of a painting.
    I know that when you take a photo with a white wall in the background that the light falls off gradually and tends to make the white wall appear grey. So that’s where I started (Click on the screenshot to enlarge).color-curves--gimp

    • A. First I created a transparent layer and put it at the top of the stack. Then using the Rectangle Select Tool, I made a small box in the upper left hand corner… with the marching ants still on I filled it with 50% grey [Edit->Fill with FG Color].  I felt it was too dark, so I filled it with 90 (too light), then 80 (just right) before I felt the grey would be close to the color the background should have been. Then I removed the marching ants, Shift+Ctrl+A.color-block-greygreys_LR1000
    • B. Next, I made a duplicate of the layer duplicate-layer created in step 1. Then I made Sample Points of the grey square (click on that layer to create sample point), and a point on the white board the snail shell is sitting on. To create a sample point, Ctrl+Left Click on the Ruler section then drag to the desired point. To see the sample point information go to Windows->Dockable Diaglogs->Sample Points. You can click on the drop-down box to show Pixel, RGB, HSV, or CMYK information. I left it on Pixel. The background sample point originally read:
      • R 212
      • G 205
      • B 202

      Whereas, the grey 80 read:

      • R 204
      • G 204
      • B 204

      Which meant that I wouldn’t have to alter the curves very much at all.

    • C. Clicking on the duplicate layer to make it active, I went to the curves adjustment [Color->Curves]. The mouse icon becomes a eyedropper, so I clicked near sample point #2 — which will give you a vertical line in each of the channels on the curves adjustment window. Using that vertical line I adjusted the Red, Green, and Blue channels to get the same values as the 80 grey sample point. It’s a fine adjustment (as you can see I didn’t get 204, but rather 206 for the green value).  Then click OK.
  3. I felt that the fill light on the left side of the image was too blown out, so I darkened some of that area.  I also felt that the main light area on the right side was too dark, so I lightened some of that area.  I used the technique I describe in this post.
  4. Next, I played around with the Local Normalization Filter3 and Luminosity Masks as described in this post.
  5. Lastly, I used the Wavlet Decompose Filter to add some sharpness, I talk about that filter in this post.

Kind thoughts and comments welcome! 😀

Until next time…

wilber1 GIMP is Open Source software that is available for all platforms (Linux, Mac, and Windows), it is a photo editor that does many (if not all) of the things you can do in Photoshop. You can download it for free here. The GIMP online manual can be found here.

Like Wilber? You can get him here.


2 DarkTable is Open Source software that is available for Linux and Mac, it is a photo editor that does many of the things you can do in Lightroom, like process RAW files.  You can download it here.  The DarkTable online manual can be found here.

3 G’MIC Plug-in for GIMP is a plug-in that has a ton of filters, you can download it here.

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