There must be something basic that I fail to understand about layers

[ann_overland]

<p>I am trying to improve my image processing skills, and I am using Gimp. So far I have adjusted the images by applying the changes directly to the image.<br /> <br /> Now I was trying to do the same thing by using layers with no success. And I can't find out what I am doing wrong by Googling it either. I must be using the wrong search words or I do have a basic misunderstanding about layers. I have used layers with some "success" when it comes to creating things that you can see through (opacity less than 100%).<br /> <br /> Anyway - here is what I thought was possible to do:<br /> <br />1) Create the background by opening the image you want to improve<br /> <br />2) Add a copy of the background layer as a new layer. Correct the colors and light of the image by using levels<br /> <br />3) Add a copy of the background layer as layer two. Correct the sharpness of the image here with the tools you have for that, with a brush and/or with an unsharp mask. I am new to the unsharp mask too, but I seem to have gotten that right in this layer.<br /> <br /> The problem:<br /> <br />The corrections are only visible within each layer. Shouldn't it be possible to get a nice, colorful, sharp image by doing these steps? The must be something that I do wrong, since I can't "see through" the stack of layers, if you understand what I mean.<br /> <br /> Help, please...</p>

<p> </p>

[paddler4]

<p>I don't use Gimp, but I suspect that the problem is that you are adding a copy of the background layer on top of a layer with edits, blotting out the edits. At least in PS, the order of the layers matters. At least in PS, you can add add an adjustment layer without adding a copy of the background layer, which avoids the problem.</p>

[george_ghio]

<p>http://gimp-savvy.com/BOOK/</p>

<p>Buy the hard copy or download it for free. I used GIMP for a number of years and found this book to be invaluable.</p>

[ann_overland]

<p>Dan, I just googled adjustment layers and Gimp, and found out that it is missing in Gimp. To think of all the hours I have spent trying to figure this out. Thank you for your answer, it was most helpfull.<br>

<br /> Here is a link where they discuss the problem. I found some good tips there:<br>

<br /> <a href="http://www.cambridgeincolour.com/forums/thread1259.htm">http://www.cambridgeincolour.com/forums/thread1259.htm</a></p>

[Mike D]

<p>I have the same issue with layers in Photoshop. When starting to post process an image, I make another file copy of the image; I never make changes to the original image file. I then post process using sharpening, filters, plugins etc. Sometimes I create a new layer so I can change the opacity after using the filter, but I always flatten the file before saving it and making additional changes. I simply just don't like playing with a bunch of layers and remembering what's in each layer. Also, the more layers you keep, the larger the file, and I mean really large. If at a later date I don't like some of my changes, I just start over again with the original, unaltered file. Yes, someone who uses and saves layers doesn't have to start over again, but maintaining layers just seems like a bunch of work. I suspect I'm one of the few users of Photoshop that use this practice.</p>

[ann_overland]

<p>Hi George, I bookmarked that page today, actually. The problem with buying books about software, at least how I see it, is that there are often new releases of the programs out there before you have read the first chapter :-)<br>

The book you are referring to, is also online to be read, and that it fine. I found it to be a bit complicated to understand, but I was looking for something else soo I might have spent too little time there.<br>

<br />I like the video tutorials, where you can see what they do. At least if you can find the good ones, where they tell you what you need to know and where they don't speak too fast or work too quickly.<br>

<br /> Anyone who have found some good Gimp video teachers on YouTube?</p>

[ann_overland]

<p>Hi Michael, I haven't actually missed not having the adjustments in layers. Just thought that I would find out what it was all about.<br /> <br />I convert the Nikon raw files to tiff files in ViewNX 2, and the quality of the images after the adjustment without layers seems just fine to my eye.<br /> <br />I have just been playing around a bit with layers while trying to make a logo and turning it into a brush, and I guess I couldn't have done that without them. I am kind of proud of that little logo, it took a while for me to get it right. Now I can just paint it on the images, and it is easy to adjust color, size and opacity of the logo.<br /> <br />I believe it is much easier to create brushes in PS, though. Well, it is easy in Gimp too, once you have found the missing link :-)</p>

[ethervizion]

<p>You are misunderstanding the basic concept of layers. You're are thinking of them as additive processing steps (Lightroom works like this, but it's not called layers). In reality, layers are are like layers of transparency films (like the old days of overhead projectors). The reason why you only see your layers individually is because they have no transparency! If you take one layer which is completely opaque and lay it on top of another, you will only see the top layer.<br>

As mentioned, the basic editing process that you are following is best achieved with adjustment layers. But, even in Photoshop, these only go so far. You're better off doing non-destructive editing in a program like Lightroom.<br>

In summary, traditional layers are really only useful if they have some transparency to show what's beneath them. For example, if you only want to selectively sharpen, you could make a copy of the layer, sharpen the one below, and then "erase" (make transparent) the portions of the upper layer where you want to reveal the sharpened image content from the lower layer. If this type of selective editing is not what you're trying to achieve, then essentially layers are not the right tool for what you want to do.</p>

[ann_overland]

<p>Hi Karl, I do understand the transparency of layers. And I am not thinking of them as additive steps. But there might be many other things that I don't understand about layers. I don't know how the adjustment layers works in Photoshop.<br /> Some years ago I did try Lightroom for a month, but I did not like it. I ended up spending a lot of time only to achieve what ViewNX had already done for me - with a much better result. I use the camera settings and am carefull to get the exposures and white balance as accurate as possible in camera. Then there is little work left to be done. Gimp is mostly used to adjust levels and to sharpen the image. And if necessaray I also saturate a bit more and adjust the color balance. I find the sharpening tools in Gimp great. Since I sharpen a bit in camera, most of the time I only have to use a "brush tool" to do some minor selective sharpening. The amount of local sharpening is adjustable from 0 - 100% there.<br /> I also find for some reason that it is better to do the adjustments in Gimp rather than to do further adjustments in ViewNX2. In most cases I am not able to see the destruction (I can sometimes see it in the histograms after the post processing, but I am not able to see it in the picture). But for a profesional photographer I guess things look a bit differently.<br /> I did not quite understand why you had to cut a hole in a layer to do selective sharpening on an image. Is there no "brush sharpening" in Photoshop? Or where you thinking about unsharp mask?</p>

[lachaine]

<p>I use GIMP a lot, and frankly, I don't see why you even need layers to do the things you are doing to the images. If you are using them merely to avoid touching the first layer itself (and undo is just as good for this), you have to merge the layers into one image if you don't want the operation to apply just to the active layer. Simple, everyday photographic operations you do on photos don't really require layers at all.</p>

[ann_overland]

<p>Hi Pierre, I haven't really felt the need for layers to do the post processing that I normally do. If I understand you correctly, nor have you.<br /> <br />I wonder what the adjustments layers in Photoshop are normally used to, though. There must be some benefits to them, since they exist and since some people would like to have them in Gimp?<br /> <br />And I was wondering, if the corrections are done in layers and then merged with the background, will the "destruction" of the images be less then if I apply them directly to the images (only at the background layer)?<br /> <br />I believe that there are still some missing links for me here :-)<br /> <br />By the way, I learned about transparency in layers when making The Spiral Universe:<br /><br /><a href="../photo/15194372&size=md%20">http://www.photo.net/photo/15194372&size=md </a><br /> <br />It is made by the use of blend tool only. It consists of many layers in different layer modes. It was really fun to play around with all the possibilities of the blend tool and layer modes.</p>

[jcuknz]

<p>I would forget about GIMP if it doesn't have adjustment layers and get yourself a copy of Paint shop Pro X4 which currently is only about $60 and a top line programme up with the best. With a freindly and helpful support group at pspug.com<br>

I cannot imaging working without adjustment layers, the most important and valuable tool in PSP and Photoshop.</p>

[ann_overland]

<p>Hi JC, what do you normally use the adjustment layers for?</p>

[John Seaman]

<p>When I first started to play around with images I always found it annoying how many people treat layers as some kind of religion. As I’ve gradually learned more about image editing I’ve come to the conclusion that many routine jobs, for example setting levels, sharpening, minor cloning etc can be done without bothering with layers at all. If you are worried about modifying the original image file, just save it under a different descriptive name. There are some other tasks you can do with or without using layers, for example exposure adjustment (dodging and burning). You can use the dodge and burn tools in the toolbox, but its better (in Photoshop) if you add an overlay layer, fill with 50% gray, then paint over the areas you want to lighten with a white brush, and paint over those to be darkened with a black brush. This gives much better control and you can check your progress by turning on and off the transparency of the overlay, or just bin the overlay and start again if you aren’t happy. Finally there are some things, like any kind of combination of images, text, designs which can only be done with layers – and by naming each layer to help you keep a clear idea of what it does.<br /><br />Adjustment layers come into their own when you want to apply the adjustment to a part of the image only. By setting up (for example) a Channel Mixer layer you can turn the image into monochrome, then use the black or white paintbrush on a layer mask to select the parts of the image you want the monochrome to apply to.<br /><br />Another example of layers, if a scene has very bright and dark areas, use a RAW converter to create two versions of the image at different exposures, one dark, one light, put the light version on the top layer and use a layer mask to paint out the bright parts, revealing the darker areas in the layer beneath.<br>

By the way I'm no Photoshop guru but I feel some sympathy with anyone who finds the constant barrage of stuff about how wonderful layers are a bit intimidating.<br /><br /></p>

[ann_overland]

<p>Wow, John, thank you so much for a great answer. It was most helpfull. I know that you need the layers when you combine images, text and designs. That is easy to do once you have tried it a couple of times. I have yet to try out some of the functions you describe here, but I am 95% sure that I can do all these steps already in the present version of Gimp. There are layers, layer modes, layer masks, the channel mixer and the dodge and burn tool there. Could it be that Gimp is not missing the "adjustment layers" after all? Are the adjustment layers any different from a regular layer or are they just named that way depent on how a layer is being used?<br>

<br /><a href="http://www.gimp.org/tutorials/Selective_Color/">Link to a hand coloring tutorial in Gimp</a></p>

[ann_overland]

<p>Here is a <a href="http://www.gimp.org/tutorials/Blending_Exposures/">link</a> with a tutorial on how to blend exposures in Gimp. The author is using two images of the same scene with different exposures, but as John S. writes, you can do the same thing in post by making two images from one with different exposure settings in your raw converter. Alternatively, you can make a copy of an image and do levels adjustments on one of them and combine the two images.</p>

 

[jcuknz]

<p>Ann an argument, maybe dubious :-), for using adjustment layers is that you are not working on the original*. I use it for just about every adjustment to a photograph except for sharpening and softening. If you are not using an adjustment layer and you don't like what you have done then you probably need to start all over again and repeat all the good things you did prior to the wrong thing. Then another use is to have more than one AL in the stack and toggle between them to consider different treatments. Using the AL as a mask is a superior way to work becuase if you don't like what you just did when using black you can replace what you 'cut' in error by painting with a white brush. This can be tonal adjustments or apparently masking around an object but I have yet to get to grips with that, only recently learnt that :-)</p>

<p>With regard to your last message the AL doesn't have to be black or white controlled but any of the 254 steps of grey between, and long before I learnt what HDR was I was doing similar by lightening different ares of a photo with the single AL but with different levels of grey. Once you have an area selected you can try different levels of grey using the flood fill tool until it looks right.<br>

You do not need a "raw converter" since it is easy enough to duplicate and organise at different layers in the stack in both PS and PSP. Then for different groupings of treatment you can organise the layers in groups so the AL only applies to its own group.<br>

Yes definitely ALs are the best thing since sliced bread :-)</p>

<p>*I have never understood the PS Gospel that the first thing you do is make a duplicate becuase the original is back in the foler and what you see on the screen isjust a copy ... but of course people until they learn better often use the 'save' command instead of the 'save as' ... but that is probably another subject.</p>

[ann_overland]

<p>What is AL? Is it the adjustment layers? I am not getting everything you write, JC. I obviously don't know enough yet. There is still a missing link regarding what an adjustment layer is. Is it just a regular layer or is it something else?<br /> <br />There are still no grouping option for layers in Gimp. I look forward to that being possible. I am very happy with most parts of Gimp. Maybe it is because I don't know what I am missing. But so far no one has been able to tell me what I am suppose to miss, so I guess I will be living happily in the Gimping world for a few more years. They keep improving it, and it is getting better and better. The developers are doing a great job.<br /><br /> As a principle I don't like to be dependent on one company....they can eat you for breakfast before you know it.</p>

[raczoliver]

<p>One advantage of an adjustment layer is that you are not placing a new copy of the whole layer below, but you are only making an adjustment to it. For example, if you add a curves adjustment layer to a layer, the adjustment layer will only control the curves, and you can go ahead and do any other editing in the layer below. With normal layers, any editing you do below another layer will not be visible unless the opacity of the top layer is less than 100%, but that will make the top layer less visible...</p>

<p>If file size matters for you, an image with a bunch of adjustment layers has a much smaller size than a bunch of normal layers.</p>

<p>And like many said before, you can always go back and do adjustments to the adjustment layer without ruining the image. Say you wanted to increase the contrast of an image. You could of course just duplicate the background layer and increase the contrast on the duplicate, but what if you realized you increased it too much? What if you realized you increased it too much ten minutes later, when you have done a thousand things since the increase of contrast? You can't just readjust the contrast of that layer, because if you already blew out the highlights and lost detail in the shadows, there is no way you can bring that back. With an adjustment layer, any time you realize you overdid something, you can go back and readjust it without losing any detail.</p>

[ann_overland]

<p>Hi Oliver, thank you for your answer. I think I am getting it now. I watched a few videos. It seems to me that what you can do in adjustment layers are the same thing that you can do to your file in a raw file converter. It is like using ViewNX2, except that you have the toolbox there to make selections and to do the changes for only part of your pictures. And you can alter the exposure of the file in the dark, medium and light areas (called levels there) and not just for the whole file (called exposure in a raw file converter). I guess you can also change the levels within the red, green and blue channel there (levels). They call it adjustment layers, but it looks to me like this is raw file convertion being possible not only on the whole file but also on part of your file. Am I being right? </p>

[raczoliver]

<p>I think you have it more or less right. I would recommend that whatever you can do in the raw converter, do it there, but there may be a couple of things that that your raw converter cannot do but photoshop can, or the results just look different. What raw converters cannot do as of now is applying masks to layers, which is very useful in my opinion.</p>

<p>It is not really raw file conversion, though, because you don't have all that data to work with. That's why you should get as close as possible to the final image in the raw conversion. If you open a file in photoshop that is missing details in the highlights or shadows, you can never get that detail back in PS, while different raw conversion settings may do the trick.</p>

[ann_overland]

<p>I guess there are raw converters out there being capable of doing a lot more in the conversion than you can do in ViewNX2. I cannot retrieve lost details in the shadows there. The highlights will just be blown out. You can only lighten the whole image. Unless there is a function there that I haven't found yet. Which raw converter do you prefer, Oliver? Have you tried more than one?</p>

[raczoliver]

<p>I have tried Capture NX and Lightroom, which for the raw conversion part is the same as Adobe Camera Raw. They are all very good, but with a very different layout. Lightroom is good for cataloging your pictures too, if you take a lot of pictures and are having a hard time keeping track of the files, I recommend it. Otherwise, with Nikon cameras, Capture NX2 often does the job quicker, but it is a highly personal choice. I think you can download a trial of each.</p>

[ann_overland]

<p>Ok, thanks Oliver.</p>