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Darkening specific parts of a photo

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GIMP Community Discussion and Help Forums - Tutorials, Scripts, Brushes, Patterns, Gradients and Filters

Darkening specific parts of a photo

Sat May 02, 2020 3:50 pm

GIMP Version: 2.10.18
Operating System: Windows
GIMP Experience: New User



I have an old color photo that shows two people near a garden. While the rest of the colors are nice, one of the faces is bleached out. Is there a way to specifically darken the faces some, the man's shirt, and maybe the white flower in front of them? Thanks!


Image

Re: Darkening specific parts of a photo

Sat May 02, 2020 4:16 pm

On the white part there is no much "texture".
My poor try with curves.

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Re: Darkening specific parts of a photo

Sat May 02, 2020 5:27 pm

Re: Darkening specific parts of a photo

Sat May 02, 2020 5:45 pm

There is no more info left in the blown out parts, so I could only darken them a little.
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Re: Darkening specific parts of a photo

Sat May 02, 2020 5:59 pm

BTW, I also used the curves tool. If you only want to work on the lighter parts of an image, create an anchor point around the middle and only bring the upper right point down on the vertical scale on the right. See picture.

I also used a mask of a grey scale copy of the image to make the selection of the brighter parts even more precise. (Duplicate layer, right click on the layer the the layers TAB, 'Add Layer Mask' and then 'Greyscale copy of layer'.
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Re: Darkening specific parts of a photo

Sat May 02, 2020 6:49 pm

Re: Darkening specific parts of a photo

Sat May 02, 2020 6:57 pm

And with a little more work I can come to this. I really like how much detail dinasset got out of the faces. I can't get as much out of it, but I think it is better than my first attempt now.
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Re: Darkening specific parts of a photo

Sat May 02, 2020 9:55 pm

The whites are too far blown out, but here is an attempt using Curves and a mask.

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Re: Darkening specific parts of a photo

Mon May 04, 2020 5:05 am

@racer-x Nice detail in the faces. Is there something particular you've done to achieve that?

Re: Darkening specific parts of a photo

Mon May 04, 2020 10:26 am

No, just basic curves adjustment.

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Sours: http://gimpchat.com/viewtopic.php?f=8&t=18300

Many new image editors focus heavily on the color in their images, without thinking about the basic structure of the image at all. Highlights and shadows help us focus on form and shape, which is why many photographers spend time working exclusively with black and white imagery. 

But what can you do with an image in GIMP once the shutter has already been clicked? Almost anything! You certainly don’t need to be stuck with the existing tonality, and GIMP provides a huge range of tools to help you brighten and darken an image – but they’re not all created equal. 

Many editing tutorials go for the most obvious basic adjustment tools: Brightness/Contrast and Levels, but these tools are sort of like using a sledgehammer when you really need microscopic tweezers. You could use them, but you won’t get the kind of subtlety that comes from using the proper tool: Curves.

Quick Navigation

The Quick Guide to Brighten and Darken an Image in GIMP

If you’ve used Curves in another program like Photoshop or you just need a quick reminder of the basics, here’s how to use Curves in GIMP:

Step 1: Open the Color menu and select Curves.

Step 2: Click along the white diagonal line to create adjustment points at various tone sections. Move a point up to brighten the selected tones within the image, or move a point down to darken the tones. 

You’ll need to be careful about where you place your points, how many you place, and how extreme your adjustments are. Too many points with huge adjustments can completely ruin an image, but the right touch can turn a good photo into a masterpiece. 

That’s the fastest possible introduction I can give you to using Curves to brighten and darken an image in GIMP, but there’s a lot more to it! Read on for a more in-depth explanation of the Curves tool and how you can use it to make your images really pop with contrast. 

Lean into the Curves

I’m going to be honest with you from the start: Curves can be a bit confusing at first until you get the hang of how it works.

I had a colleague many years ago who fought with it constantly until one morning he came into the office and told us that he had a dream about how it worked, and suddenly he could use it much more intuitively – even as a tool for adjusting color using specific channels, which I still find deeply frustrating.

I’m still waiting on my epiphany, but we can rely on practice in the meantime. Hopefully, I can do a better job of explaining it to you, although there is something to be said for the processing power of the human subconscious – and a lot of experience and practice. 

Understanding the Histogram

The most important part of the Curves dialog is the histogram, which is shown in the background behind your adjustment line. Histograms are used throughout the world of image editing, so it’s a good idea to get used to reading them and working with them. 

If you’re not already familiar with the concept, a histogram is a graph that describes the tonality of your image. The left edge of the graph represents pure black and the right edge of the graph represents pure white, with all the levels of grey in between. The height of the graph at any one point shows how much of the image contains that corresponding tone. 

GIMP adds a helpful gradient along each axis of the histogram in the Curves dialog, which really helps to understand the concept. 

In this example, you can see that there are no pixels that fit into the very brightest range of the histogram (highlights) and also no pixels that fit into the very darkest range (shadows). In order to give the photo some pop, we’ll have to correct this too – good thing Curves can do it all! 

Brightening and Darkening Your Image With Curves

Hopefully, you’ve started to form an idea of how the tool works, so let’s get down to the nitty-gritty, shall we? In this example, I’ll take you through the process that I use to give flat images some contrast pop.

Step 1: Getting Started

Open the Color menu and select Curves. Not much to this step 😉

Step 2: Set Your Limits

The sharp-eyed editors among you may have noticed that the Curves adjustment line already has two points set, even before you add any of your own. The points are at each end of the line and are used to set the black point and the white point of your image. 

The histogram in the background shows us that this image has almost no bright white pixels, and almost no dark black pixels either, which creates a flatter-looking image. By adjusting the two existing control points at either end of the line, I can push the brightest pixels in the image into the range of pure white, and the darkest shadows into pure black. 

It is not essential to adjust these for every image, but it’s a good idea to experiment with them while you’re still learning how the Curves tool works. You’ll have to be the judge if the effect is right, so be sure to make good use of the Preview and Split View options to see your results before finalizing them.

Step 3: Contrast Tweaks

One of the most common methods for brightening and darkening an image is the “S-curve”. The idea is to modify your adjustment line into a gentle S shape by keeping the mid-tones in place while darkening the shadow areas and brightening the highlight areas. 

Again, this doesn’t work for all images, but it’s a good place to start. You’ll get more comfortable assessing what each individual image needs as you get more practice. Sometimes, the “right” choice isn’t the one that matches your artistic vision, so don’t feel limited by this guide, but trust your eye. 

If you’re not sure where to begin your adjustments, you can also move your mouse cursor over the main image window and a line will appear in the Curves dialog showing you the matching area. Hold down the Shift key and click to set an adjustment point for those tones.

Be careful when adding your points and making adjustments, though. Start slow, and always be ready with your Undo command. You can also select adjustment points within the Curves dialog and delete them using the Delete key if things get too weird! 

Also, one last important note! GIMP doesn’t support non-destructive Curves adjustments or adjustment layers, so once you click the ‘OK’ button, your changes are saved permanently to the file. You can use the Undo command, of course, but you’ll have to make all your adjustments the first using the tool since you can’t edit them later.

Advanced Curves Using Color Channels

If you want to get extra fancy with Curves, you can start using it for brightening and darkening individual color channels, instead of adjusting all of them at once as I explained above. 

Digital images on a computer are typically stored in an RGB format, which means the image contains a Red channel, a Green channel, and a Blue channel. Each channel is actually a black and white image, where white corresponds to the pure hue of the channel’s assigned color.

So in the Red channel, the white pixels represent pure red, and in the Green channel, white pixels represent pure green, and the same applies to the Blue channel. The three channels get combined to form the standard RGB images we all know and love. 

This is not my chosen method for adjusting the hue in an image, but it does have some technical uses where color accuracy is absolutely essential – or desirable.

All you have to do is adjust the Channel setting above the main Curves histogram to adjust a specific color channel (or even the alpha channel, if you have one, though this could create some very unexpected results). 

If you want to reset your adjustments, you can click the Reset Channel button to return any channel to its original unedited state. 

A Final Word

While there are lots of ways to brighten and darken an image in GIMP, Curves is the best way that I’ve found. It’s a popular tool that’s used across a wide range of programs, so it’s a very useful tool to know and understand. I learned to use it in Photoshop, but it’s nice to see a familiar friend in GIMP. 

The process of adjusting highlight and shadow is a complex one, and you’ll need a lot of practice to get really good at it – but now you know how to get started, so have fun! 

About Thomas Boldt

I’ve been working with digital images since the year 2000 or so, when I got my first digital camera. I've tried many image editing programs. GIMP is a free and powerful software, but not exactly user-friendly until you get comfortable with it, and I wanted to make the learning process easier for you here.

Sours: https://thegimptutorials.com/how-to-brighten-darken-image/
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Creating a Contrast Mask

Text and images Copyright (C) 2002 Eric R. Jeschke and may not be used without permission of the author.

Intention¶

beforeafter

In this tutorial I’ll show you how to do create a contrast mask for your image in GIMP. A contrast mask allows you to reduce overall contrast, simultaneously bringing out more detail in highlights and shadows. This may be necessary to obtain a decent print, because prints on paper do not have as much dynamic range as a monitor; if you don’t control the contrast, detail in the highlights may blow out and detail in the shadows can block up and become muddy or even black. You can of course modify your image directly in GIMP to decrease contrast, but the advantage of the contrast mask technique is that it allows you much more precise control, and gives better results.

The basic technique is to create a layer above the image that contains a B&W negative of the image. The images are combined in overlay mode: dark parts with light, light parts with dark. All the while your original image remains blissfully unchanged on its layer.

Giving credit where credit is due: I did not come up with this method. I adapted it for GIMP from a Photoshop tutorial on The Luminous Landscape web site (great photography web site BTW; I recommend it).

The contrast mask technique does some similar things for the exposure as the digital split ND filter and the blended exposures techniques. If you feel your image has exposure problems you might want to consider those techniques as well. Each one has different strengths. Occasionally this technique gives unacceptable color shifts in certain images. Sometimes it is just the ticket. Experiment to see if it can work for your particular image.

The Procedure¶

original.jpg

Here is the original example image, loaded into GIMP. The red leaves are a little too dark to make out the detail; if printed, the result would be pretty dark and muddy. At the same time, the yellow flowers have a couple of specular highlights that would probably blow out the detail if printed.

We want to brighten the dark areas a little and darken the light areas a little. In other words, reduce contrast.

Step 1¶

layers2.jpg

Open the Layers dialog. Right-click on the Background layer and select Duplicate (there is also a button for this in the bottom button bar of the Layers dialog.

Step 2¶

editlayerattrlayers3

Now double-click on the duplicate layer and rename the new layer “Contrast Mask”. (This step is not strictly necessary, but it is helpful to prevent confusion about what is on each layer, especially if you add some additional layers for other editing purposes).

Step 3¶

image2.jpg

Select the Contrast Mask layer. Go to the image window and right-click, selecting:

The image should look B&W.

Step 4¶

image3.jpg

Right-click and select

You now have a B&W negative image of your original. We’re going to combine this with the original (light with dark, dark with light) to reduce the overall contrast.

Step 5¶

layers4image4

Go back to the Layers dialog and in the “Mode” drop-down box, select “Overlay”. The result may look better in terms of contrast, but degraded in terms of overall sharpness.

Don’t worry, we’re not done yet.

Step 6¶

originalimage5

Go back to the image window and right click, selecting

You will need to experiment to find the best value, but typically a value between 10 and 30 will do nicely. After blurring the contrast mask the overall image should now look much sharper.

Click on the “eye” next to the Contrast Mask layer in the Layers dialog to rapidly compare the image with and without the mask. Similarly, turn off the Background layer if you want to view the mask to do further work on it.

The image at top left is the original, the top right is with the contrast mask.

Step 7¶

originalimagewtypcontrastreduction

It is informative to see how this technique compares to the conventional technique of using the contrast dialog to adjust contrast. I’ve tried to adjust the contrast to have the leaves appear about the same. I think the image with the contrast mask has a lot more pop! This one looks kind of flat by comparison.

Step 8¶

Histogram-BeforeHistogram-AfterHistorgram-Contrast-Reduction

To see why this is so, compare the histograms of the images. The top one is for the original image, the middle is for the image with the contrast mask, and the bottom one is for the original image with the conventional contrast adjustment.

Note how the typical contrast adjustment has lost a lot of values at both ends, but the mask technique basically preserved the entire scale.

Step 9¶

layers5.jpg

You’ll have to flatten the image if you are saving it to a typical image format like TIFF or JPEG (but not if you are saving to GIMP’s native XCF format). To do that, right-click on the image and select

Fine Tuning¶

Now that your contrast mask is created, it’s time to fine tune it. Here are some things you can do:

  • Use the “Opacity” slider in the Layers dialog to decrease the effect of the contrast mask overall.
  • Apply Levels or Curves to the contrast mask to open up the shadows or reduce the highlights further.
  • Apply the dodge and burn tools to the contrast mask.
  • Apply a layer mask to the contrast mask and use it to select only parts of the contrast mask; e.g. if you only want the contrast mask to apply to certain areas of the image (see my example of this below).

Tips¶

  • See this article for some informative tests on the effects of the Gaussian Blur step on the contrast mask.

Other Examples¶

tree.jpgtreewcmask.jpg

With a contrast mask as described above. Notice how the sky has recovered some blue, and the detail visible under the tree!

nd-original-1.jpgutsunset-wcmask.jpg

Here’s an example of how this technique overlaps with the digital split ND filter approach. Which do you prefer?

nd-filter-1.jpgutsunset-whmask.jpg

With a digital split ND filter. (left image) With a contrast mask as described above, plus a layer mask with a gradient fill, so the contrast mask is mostly applied to the area below the cliffs. (right image)

Note particularly the change in the color of the cliffs and the light part of the sky just above the cliffs, in the image using the full contrast mask (upper right). This shows how a contrast mask affects all parts of the image, unless you selectively disable part of the mask, as I did in the lower right. Note also that with the split nd filter (lower left) I was able to brighten the foreground more; I could apply a general levels tweak to the contrast mask to achieve the same thing, but it seems like more work. This illustrates a general point for me: the digital split ND filter technique is the easier approach when you’re already satisfied with half of the image, whereas the contrast mask is a better starting point if the overall image needs contrast reduction on both the dark and light sides.

The original tutorial used to appear on gimpguru.

Sours: https://www.gimp.org/tutorials/ContrastMask/

How do I brighten a part of a picture with Gimp?

Your photo is already a heavily processed JPG. Lifting up the shadows will introduce visible blurriness and other errors, which have been less offensive as dark. 8 bit JPG simply hasn't enough data left. The result is quite coarse. There's noise, JPG compression errors and too few brightness levels in the dark areas.

The next version is a test what is available in the shadows. The image is opened in a RAW image processing program and got the same treatment as a real RAW image. There's fill light, local contrast boost and radical sky blue reduction in shadow areas. The shadow has fortunately sharp border for easy selection.

enter image description here

If you zoom in you can see that the lifted shadows are very coarse behind the lake, because they were noisy and blurry and the bit depth is too low for nice contrast increasing.

But the result can still be acceptable. We can try to get this in GIMP.

The old approach to fix your photo would have been to increase brightness and contrast in shadow areas with curves and then fight back the introduced excessive colorfulness. This is presented already by others. We try something else which wasn't possible before GIMP 2.10.

GIMP 2.10 has a polar version of CIELAB color system named LCH which is especially useful and makes a new answer worth writing. We make a good colorizable BW version of the image and colorize it with blending mode Color LCH.

Colorizable BW image has grey midtones where one expects color. Too full black and white are not colorizable. We can make one by desaturating and masked contrast increasing. GIMP hasn't adjustment layers like Photoshop, Krita, Affinity Photo etc... but we can work around with layer copies.

Start by making a couple of desaturated copies of the original image layer:

enter image description here

Insert a layer mask. Let it be the BW image as inverted

enter image description here

Disable temporarily the layer mask. Move the original colored image on top and let it have blending mode Color LCH.

enter image description here

The result is quite the same as the original, but you can make radical changes by editing the BW image and its layer mask.

At first find a good Color > Color curves > Value setting which lifts the dark areas acceptably. The bright areas get too flat, but we'll fix it later:

enter image description here

We do not want to lift already bright areas. Enable the layer mask and apply curves to the mask to get some area separation. Click the mask icon to get the mask under editing:

enter image description here

Unfortunately the mask has too much details. Details suffer badly. A real man would paint the whole mask manually to get the exactly right effect strength distribution, but we can cheat. Let's apply some blur to the mask and get boosted local contrast that way:

enter image description here

Even more local contrast is available by flattening the image to a single layer and applying Unsharp Mask:

enter image description here

The version from a RAW developer program clearly has some saturation boost which is missing here due the LCH colorizing. If that sweetening is wanted, increase the saturation:

enter image description here

I guess the whole tinkering is not worth the effort if you can invest the needed time to learn to cope with a RAW developer. Photoshop's Camera Raw is the easy one, but generally they are complex. Raw Therepee is free and it can be used as plugin from GIMP.

Done

Sours: https://graphicdesign.stackexchange.com/questions/76187/how-do-i-brighten-a-part-of-a-picture-with-gimp

Image part gimp darken of

How to Darken a Line in GIMP

By Naomi Bolton

You can create very interesting shapes with lines of different shades.

When using GIMP, it is possible to lighten and darken images by changing the contrast. The built-in color levels and curve tools also provide you with methods of darkening an image, but these solutions are not ideal when working with individual lines. For the best results and greater control when darkening a line, the "Burn" tool is a good option. Alternatively, if you want to darken a line without altering the color of the original image, you can achieve this result through the use of layers.

The Burn Tool

Launch GIMP and open the image file with the line that you want to darken.

Click the "Fuzzy Select" tool and then click on the line you want to darken so that it is selected. This will ensure that the Burn tool doesn't influence any of the other lines or colors.

Click the "Dodge/Burn" tool on the toolbox or use the "Shift-D" keyboard shortcut.

Click the radio button next to "Burn" on the tool options, which is docked below the Toolbox.

Click the radio button next to "Midtones" on the tool options. This restricts the effect of the Burn tool to only the pixels of average tone.

Drag the "Scale" slider on the tool options until the Burn brush size is about the same as the line that you want to darken.

Click and drag the Burn brush over the line that you want to darken. Every pass of the Burn brush darkens the line. Repeatedly drag the burn brush over the line until you are satisfied with the results.

Layers

Launch GIMP and open the image file with the line that you want to darken.

Click "Layers" and select "New Layer." Enter a name for the layer and click the radio button next to "Transparency" before clicking "Ok."

Click the newly created layer on the Layers window so that it is the active layer.

Select "Overlay" from the drop down menu next to "Mode" on the Layers window.

Click the "Paintbrush" tool and use the "Scale" slider to adjust the size of the brush so that it matches the width of the line you want to darken.

Select "Black" as the foreground color of the Paintbrush tool. Drag the "Opacity" slider on the tool options to "50.0." Increase the value to darken it more if needed.

Click and drag your mouse cursor over the line you want to darken. If you use "100.0" opacity for the brush and it does not darken the line enough for your needs, create a new layer on top of the previous one and repeat the process.

References

Resources

Writer Bio

Virtually growing up in a computer repair shop, Naomi Bolton has held a passion for as long as she can remember. After earning a diploma through a four year course in graphic design from Cibap College, Bolton launched her own photography business. Her work has been featured on Blinklist, Gameramble and many others.

Sours: https://smallbusiness.chron.com/darken-line-gimp-45915.html
Gimp Tutorial: How to brighten shadowed subjects

Best way to lighten/darken parts of photos in GIMP 2.10

Thanks for the help. I read the two tutorials on luminosity masks and installed the script that @paperdigits suggested.

@claes Yes, I’m aware of the dodge/burn tool in the Gimp. But in the videos I have watched (mostly found through Youtube searches), no one seems to use it. Though, I did see one tutorial that used layers and the dodging tool to whiten people’s teeth in portraits. As I mentioned in my OP, it seems painting white/black on a layer in overlay mode seems to be more popular, at least in the videos I’ve seen.

@patdavid I am going to try and upload a picture to this post to show you what I mean. I would like the triangle background a little lighter, especially the borders to the triangle. I’m not sure the best way to do things like this, though I did get acceptable results using the luminosity masks script and manually painting parts of the mask that I did not want to change, like over the girl’s black T-shirt.

I’ll sometimes shoot studio stuff with flashes and my lighting ratio is off (though I try to avoid it in camera, obviously)

, so whatever I learn from this picture, maybe I could also use to make shadows lighter or darker in such cases?
Sours: https://discuss.pixls.us/t/best-way-to-lighten-darken-parts-of-photos-in-gimp-2-10/7685

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