Below is a test shot using my new Sony DSC RX100. This is at f/1.8, 1/100 sec, and ISO 125. I had Auto DRO turned on and did only a minor amount of post-processing on it.
Here is the image with no post-processing, aside from scaling it to be 1600 pixels wide for upload to this site.
This isn’t a tutorial so much as it notes for myself regarding some of my recent experimentation in GIMP. The resulting images are garish, but I find them oddly compelling.
Here is a crop of a photo that I took from my driveway. The original photo was 6000×4000 pixels. I performed the various operations described below on the full size image. Only later, after I saw what the image looked like after doing various manipulations, did I crop it to 1600×1080. It is a kind of blah photo. Aside from the crop, I performed no other manipulations on this image. I should note, however, that it was one of the HDR images produced by my NEX-7.
Next, I performed one round of Gaussian Blur, Grain Extract, and Grain Merge on the photo. I used a blur radius of 50 because I noticed that I was getting a large halo around trees and along the skyline when I used large values. I still need to do more experimentation to find an optimal value. Alternately, it may be possible to mask the problem areas to avoid this issue. Here is the result:
In Easy Overprocessing with c2g, I found about GIMP’s c2g filter. I’ve tried the techniques described on that page, but haven’t yet gotten similar results. It may be that I’m missing a step. Another interesting article about c2g is How to Make Stylish Black & White Digital Photos with the GIMP. I’ve skimmed it and it’s worthy of further study. Another good article is Black and White Conversion with GEGL’s c2g (color2gray) in GIMP. It provides some very, very helpful hints on how to best set some of c2g’s parameters.
The c2g operation converts a color image to grayscale, but the resulting grayscale image can be much more striking than just using Colors->Desaturate… In GIMP 2.6.11, the c2g operation is found under Tools->GEGL Operation… From there, a dialog will pop up, at which point,you need to select c2g from the menu. Here is what the crop looks like after subjecting the entire 6000×4000 image to c2g with Radius=500, Samples=10, and Iterations=10.
Here is what a desaturated image looks like using Colors->Desaturate… I ended up using a portion of this image for the sky.
The c2g version appears to have more texture to it. The sky, however, turned out to have too much texture for my taste, so I created the second version to use for the sky alone. I applied a layer mask containing only the sky to that layer and an inverted mask to the c2g layer. With the masks applied, I set the layer mode to Grain Extract for both of these layers. Here’s what that ends up looking like:
Note that the sky has a fairly smooth texture to it, but the buildings and even the street appear to have a significant amount of texture.
Next, I duplicated the blur-extract-merge layer that I started with, put it on top of the layer stack, and set its mode to Grain Merge. Here’s the result with those four layers visible:
This might actually be a good place to stop, but I decided to see what it looks like by duplicating the two grain extract layers and the top-most grain merge layer and then placing those layers in the correct order on the top of the layer stack. Here’s the result:
Performing another round of duplicating the grain extract and grain merge layers and placing them at the top of the stack produces this image:
I wanted the sky to be a deeper blue, so I added a grain extract layer of the desaturated sky with the opacity set to 71%. Here’s the GIMP layer window for the upcoming image:
Below is the final image. It may be that one of the earlier images is “better”, or maybe they’re all just awful. I’m too close to it right now and probably need to look at the whole thing again in a few days. It is interesting though to see the variety of contrasting colors obtained using this technique. At no stage in the process, except for the last step where I fiddled with the sky color, did I actually choose any of those colors. They just came out on their own by iterating grain extract / merge operations on the grayscale image produced by c2g.
I took the photo below while hiking at McDowell Mountain Park recently. Kind of boring, right?
Actually, that’s not quite how it looked out-of-camera. I cropped it to show half of the flowering plant. I thought that showing half of the plant with the rock to the left looked more interesting.
If you duplicate the layer – it’ll be named Background in GIMP – and then do a Gaussian Blur with a 150 pixel radius, it’ll look like this:
The blur radius you use will depend upon the size of the image that you’re working on. I was working on a 3510×3593 pixel image, so a fairly big blur radius seemed like a good idea. If you’re working on a smaller image, you’ll want to adjust it accordingly. Don’t be afraid to experiment. (Since first posting this, I learned that using a large blur radius often creates large halos. It’s probably best to try a smaller blur radius first, of perhaps only five pixels or so.)
Next, set the layer mode of the blurred layer to Grain Extract. I don’t claim to understand what it’s doing, but here’s what it will look like when you enable the visibility on the Background and the blur+extract layer – that’s what I named that layer. If you don’t name the layer, GIMP will just add “copy” and then “copy 2”, etc. after the layer name. There’s nothing wrong with this for experimentation, but once you have three or more layers, it starts to get confusing which is which.
Now, duplicate the Background layer yet again and put it at the top of the layers list. Change the layer mode from Normal to Grain Merge. Here’s the result – I named this new layer the same as the layer mode, just to keep track of it more easily:
If you duplicate the blur+extract layer again and move it to the top of the layer list and then duplicate the grain merge layer again and move it to the top of the layer list and then add a slight S-curve using the Curves tool, the image looks like this:
You could repeat that last step several more times if desired, but I decided that this result was vivid enough and decided to stop. If it ended up being too vivid, but the previous result wasn’t quite vivid enough, you can move the opacity slider in the top-most layer which, for me was named grain merge 2. Moving the slider to the left, thus decreasing the opacity of that layer, will allow you to fine tune the result.
This photo was taken several minutes before sunrise at McDowell Mountain Park. Once the sun actually rose, the orange glow in the clouds pretty much disappeared.
Today’s fitness hike started at the Trailhead Staging Area. We hiked about a mile of the Pemberton to the Scenic. We then hiked the ridgeline of the Scenic Trail and descended the big rocky hill towards the wash. Just before entering the wash, we turned left onto the new trail which took us to the Horse Staging Area. From there we crossed the main park road and hiked the service road, crossing the Sport Loop twice. That dumped us into Stoneman Wash where we hiked back to Pemberton. From there, we hiked nearly a mile back to the parking area. Total distance was 7.1 miles.
There were five of us today: Janet, Bob, Linda, Marilyn, and me.
A view from the Scenic Trail:
Another view from the Scenic Trail. Red Mountain is visible in both of these shots.
It’s 64 degrees and windy!
