Showing posts with label Photography. Show all posts
Showing posts with label Photography. Show all posts

How To Sharpen A Second Life Photograph With The High pass Filter In Gimp


Its always been my experience that raw snapshots taken in Second Life are not as focused as they could be. They tend to be slightly undefined. Taking snapshots with the Black Dragon viewer makes a difference, but can be very impactful on PC resources. Whichever viewer you use, knowing how to sharpen a Second Life photograph is essential, as its one of those select tools that can help make your images pop.


The image used for this tutorial was taken at Frogmore, a very picturesque sim where all Second Life photographers will find something to inspire them. The destination guide describes it very well:


Frogmore is a natural, photogenic, and fully immersive experience inspired by historic Cornwall, England, bordered by the Celtic Sea and the English Channel. Frogmore is rated Moderate and open to the public; please join the free group for rezz rights and enjoy the lavish experience of the Cornish Riviera.


Sharpening A Second Life photgraph With The High Pass Filter In Gimp

There are a number of ways to sharpen a Second Life Photograph in Gimp (some of which will be covered in later tutorials), but this technique works well and is quick and easy.

1/ Open the image in Gimp.

2/ Click on the icon to the bottom right of Gimp (highlighted in red above), to duplicate the image.

3/ The two image layers can be seen to the right.

4/ This step isn't strictly necessary, but it will stop the high pass filter from highlighting colours. With the top layer active, select Colors > Desaturate > Desaturate.
This image is here so it will be the thumbnail
on the homepage. Blogger is rubbish.


5/ This window will open. The Mode drop down menu offers different desaturation types. Here Lightness (HSL) has been selected.


6/ The desaturated image will look something like the above.


7/ With the desaturated image still the active layer, select Filters > Enhance > High Pass...


8/ The top layer will look something like the above, and the High Pass window will be open.


9/ Set a value for the Dev option. Here 15 has been selected. A little intuition is needed here because a few things will affect how much or how little high pass to use. Image size is one factor that may influence this. 

10/ The level of detail shown in this high pass layer looks about right.



11/ Click on the Mode drop down button to the right, highlighted above in red.


12/ From the drop down list select a blend mode. The section beginning with Overlay and ending with Hard Mix are the blends that work well with the high pass filter. 

13/ Here, hard light is the blend thats been selected.



14/ Your image should now be much sharper, although it can be tweaked a little more. If you want to sharpen the image even further the high pass filter layer can be duplicated, the blend mode can be changed, and the opacity adjusted. 


To see the difference the high pass filter can make, below is the before and after. Click to enlarge if you need to.



The effect may not be too dramatic here, but this is a very flexible method for sharpening images, and you're free to play around and experiment. 


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How To Remove Haze From A Second Life Photograph Using Gimp

One of the Second Life features that can really make an image stand out is the Environment settings. A technique I often use is to adjust the haze sliders so the sky and land or sea blend together, thereby avoiding the harsh horizon line that is sometimes too evident in Second Life pictures.

The haze effect however often affects the entire image including the foreground. If this is the effect Second Life photographers are looking for thats fine, but if not there is a way around this. This tutorial will show three methods of removing the haze from a Second Life image using Gimp.

The original image used for this Gimp tutorial was taken at Clockwork Bird. Take a few moments to visit this brilliantly constructed location.

If you're looking for methods to remove haze from real world photographs then these methods will work just as well.

There is also a video version of this tutorial on the SL-Inspiration YouTube channel.

Click on each image in turn to view full size.

Method One: Levels I

1/ Open the image in Gimp.

2/ Select Colors > Levels (highlighted in red, above).

3/ The above window will open. The Input Levels has three trianglular handles that can be moved to adjust this setting. For this tutorial we're interested in the two outer handles.

4/ Grab and drag one handle with your cursor by holding down the left mouse button. Adjust the handles using the above image as an example, until you're happy with your image.

5/ The haze should now be markedly reduced in the foreground of the image.

6/ Your image is now ready for further editing, or exporting.

Method Two: Levels II

1/ With the image opened in Gimp, make a duplicate layer by clicking the icon highlighted lower right. Make sure the top layer is active.

Now select Colors > Levels again.

2/ This time we're going to drag the right handle on the Output Levels towards the middle of the Levels window

3/ Adjusting the slider will make the image cloudy, as above. The amount of cloudiness will differ from image to image so a little trial and error will be involved.

4/ From the Mode drop down menu select Soft Light.

5/ The haze should now have cleared from the foreground, although the image as a whole may look a little blown out.

6/ To compensate for this, adjust the opacity of the top layer until you're happy with the image.

7/ The layers can now be merged, and the image exported from Gimp.

Method Three: Curves 

1/ This method is very similar to method two, except this time we'll be using the Curves selection.

Start by duplicating the image so there are two copies in the Layers panel. Make sure the top layer is the active layer. Now select Colors > Curves.

2/ This window will open. The Curves window lets any part of the line be dragged to form a curve. For this tutorial however we're just going to adjust the top of the line, highlighted in red.

3/ Grab the top node with the cursor and drag it into a similar position to the image above. How much you move this node will depend on your image. You're aiming to get a cloudy appearance, as in method two.

4/ The top layer should look something like above. In the Mode drop down window select Soft Light.

5/ The opacity of the top layer will probably need adjusting.

6/ When you're ready merge both layers and export.

Below is the original image to compare the results with.

As you can see, removing haze from a Second Life image is quick and easy. All three methods here produce similar results, although perhaps two and three need more trial and error than the first. I particularly like the foreground contrasted with the background receding into haze these methods produce.

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Remove The Background From An Image Using G'MIC in Gimp

In this blog we've previously covered a number of methods to remove the background from an image. The difference with this method is, whilst it works very well with images with a plain background, it can also be used to remove a complicated background scene, leaving just the foreground subject - which is what we'll be doing here.

For reference here's the other background removal methods already described in this blog, all of which are good to know:
All of the above methods have their pros and cons, and this is also true when using G'MIC. For instance, once a complex background has been removed, the image may need more editing and tidying up. Also, if the subject has messy detailed hair some of this detail will almost certainly be lost in the editing process.

If you prefer, there's a video version of this tutorial on our YouTube channel.

The G'MIC Plugin

G'MIC is an invaluable plugin for Gimp and has an incredible number of options for manipulating images. To install the plugin go to the G'MIC download page and click on the download link for Gimp. Once downloaded click on the executable and the rest of the installation will take care of itself. The next time Gimp is opened G'MIC will be installed under the Filters menu.

Remove The Background From An Image Using G'MIC

To remove the background from an image using G'MIC follow these simple steps.

The images here can be clicked to view full size.

1/ Open the image in Gimp, then select Filters > G'MIC.

2/ The above window will appear. From the list select Contours, highlighted in red.

3/ From the drop down list select Extract Foreground [Interactive]

4/ Settings for Extract Foreground will appear to the right of the window. Add a little feathering, highlighted in red, so the extracted foreground doesn't have jagged edges. A low number (here 0.04 is used) is all thats needed.

When you're ready hit the Apply button, lower right.

5/ The above window will open with the image loaded into it. This is the window we'll be using.

6/ To select the area of the image to be kept left click inside its outline. Green dots will mark where you've clicked. These dots do not need to be tightly clustered or too close to the edge of the foreground subject.

7/ To select the area to be removed right click to add red dots outside of the foregrounds' outline. Again, the dots don't need to be closely spaced or too near the edge of the subject.

8/ When you're ready hit the Spacebar on the keyboard to preview the background removal. As you can see it works well, but needs some adjustments.

9/ Both the red and green dots can be dragged to new positions. Left click and drag for green dots, and right click and drag for the red ones.

More dots can be added if they're needed. Their position is not ordered, so just place new dots where they're needed.

If you accidentally left click and create a green dot where you wanted a red one, just right click on it to turn it red. Visa versa for red dots where you wanted green.

If you add a dot by mistake, hit the backspace tab on the keyboard to remove it.

10/ As you can see it can take a little trial and error to get all of the dots in the right places. There's no undo function with this process, but you can continue to edit to get what you want. Just hit the spacebar each time you want to preview the editing.

11/ To zoom in to an area use the mouse wheel.

12/ When you've finished editing the image hit enter on the keyboard.

13/ Now hit OK bottom right of the G'MIC window.

14/ We're now back into the regular Gimp image window. To the right you can see G'MIC separated the foreground and background into different layers.

15/ Here the background layer has been deleted and a plain white layer added so the contour of the foreground can clearly be seen.

Some of the outline is still quite rough, and whilst it could be tweaked more using G'MIC, since the background has pretty much gone, removing the remnants will be straightforward. For this image I just needed to use the Eraser.

16/ This is the image after being cleaned up.

17/ Here I added a random background to show how the cleaned up foreground can be used.

Further Resources 

Whilst G'MIC isn't the only way to digitally remove an image background it is probably as good as you'd expect for a free option. Here are a few alternatives which it can more than compete with.

Remove Image background is a website that allows users to upload an image, and with the click of a button remove the background. Whilst it states its free, this is only true when images of a certain size are used. If larger images are uploaded the background will be removed but the final image will be resized.

If you want larger image sizes the website offers a subscription service, as well as a pay as you go service.

Cutout 8 is downloadable software that does a very similar job to G'MIC, although it offers more options. It comes in with a price tag of $99.00, so have fun with that. There is a 7 day trial version if you'd like to try it out.

Ashampoo offers the earlier Cutout 7 version of the above software at a reduced price of  $21.00, so this may be an alternative worth considering. Although the website states its on offer, this seems to be a permanent rather than a time sensitive arrangement.

Thats all there is to removing the background from an image using G'MIC in Gimp. Whilst it may seem a long process its actually quite quick and easy, although it may take a little practise. Like all background removal methods its not perfect, but this is the best way for removing detailed backgrounds, and as good as any of the above alternatives.
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