Selecting complex objects

AT
Posted By
als_trash
Jun 16, 2006
Views
1011
Replies
12
Status
Closed
Hi All,

I’m trying to select just the leaf in the following picture: http://grove.ufl.edu/~ashenkin/1-2-19.jpg

I’ve tried using magic wand in various steps, and it gets pretty good if I work at it for a while using channels. The problem is that I have about 120 of these images to process and would prefer to find a better way to do it. I’ve downloaded Mask Pro 3, and that doesn’t seem to do as well as just using the magic wand when I set up keep and drop color pallets.

I’m thinking of this problem in 2 ways: one part of it is selecting based on color. The problem is that, between the leaflets, the color of the white background gets shaded and looks rather like the color in some of the leaflets. So the second part I would like to incorporate is a sense of edge in the image, rather than pure raster colors. It seems to me this should be a doable task, but I’m not sure if the tools are available to accomplish it.

Thanks for any thoughts!

Best,
Allie
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complex object select

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R
Roberto
Jun 16, 2006
I would go with quick mask mode, zoomed in a good amount and a small hard edged brush. Most masking plug-ins just don’t cut it.

R
AT
als_trash
Jun 16, 2006
Thanks R. The problem with that approach is that it would suck up tons of time. As I mentioned, I’ve done pretty well with the magic wand, which is quicker than a quickmask, but still looking to get a bit quicker and sophisticated, if possible. Thanks again.
E
embee
Jun 16, 2006
wrote in message
Hi All,

I’m trying to select just the leaf in the following picture: http://grove.ufl.edu/~ashenkin/1-2-19.jpg

I’ve tried using magic wand in various steps, and it gets pretty good if I work at it for a while using channels. The problem is that I have about 120 of these images to process and would prefer to find a better way to do it. I’ve downloaded Mask Pro 3, and that doesn’t seem to do as well as just using the magic wand when I set up keep and drop color pallets.

I’m thinking of this problem in 2 ways: one part of it is selecting based on color. The problem is that, between the leaflets, the color of the white background gets shaded and looks rather like the color in some of the leaflets. So the second part I would like to incorporate is a sense of edge in the image, rather than pure raster colors. It seems to me this should be a doable task, but I’m not sure if the tools are available to accomplish it.

Thanks for any thoughts!

Best,
Allie

Go into your channels and identify the channel that has the best contrast between the leaf and the paper (don’t worry about the rest of the image.) I guess it will be the green channel (in RGB) – I don’t have Photoshop on this computer so I can’t work on it myself.

Now, duplicate the channel (using the arrowhead flyout on the Channels pallette). Working on the duplicate channel ONLY, call up levels and adjust the three sliders so that the leaf is perfectly seperated from its surroundings – don’t worry that you are mashing this channel to pieces, it’s only for a selection!! You can make very extreme adjustments with the three levels sliders – the idea is to break the leaf shape away from its surroundings.

Now, get a paintbrush and paint around the image in black and white as necessary so that the leaf is absolutlely cut away from everything else. Go back to your RGB composite channel, go Select-Load Selection and choose the channel you just created. Your marching ants should show a pretty clean selection now.
G
grannysdc
Jun 16, 2006
A simple easy way of Masking out Difficult Images in Photoshop is to use Color range then use Channels to help mask out a complex objects with clean edges as presented in the Photoshop Tutorial by COLIN SMITH at: http://www.photoshopcafe.com/tutorials/masking/masking.htm Granny likes simple and easy

wrote in message
Hi All,

I’m trying to select just the leaf in the following picture: http://grove.ufl.edu/~ashenkin/1-2-19.jpg
AT
als_trash
Jun 16, 2006
Thanks Mike and Granny,

The idea of using levels is a good one.

Mike, the one issue with your method is that some of the pixels I don’t want are of similar color to those I don’t want. So, adjusting the levels doesn’t quite help me all that much. Algorhitimically, these similarly-colored pixels should be somewhat separable through edge detection, which is what I was getting at before. Those pixels could be dealt with, as you mention, through use of a paintbrush/pencil. Again, we get into the issue of time-consumption.

Granny, I think Colin’s algorithim amounts to the same method as Mike’s, with some good ideas of how to fill in areas which were spotty.

Thanks for both your ideas – I appreciate your input.

Best,
Allie
R
Roberto
Jun 16, 2006
Actually, not as much time as you think. Doing it with a plug-in you have to learn the plug-in and then you have to fix the less than perfect masking generated by the plug-in. This will take more time than Quick Mask mode and a paint brush. Using the lasso tool or other methods and do a good job at it will take probably more time. If you zoom to say 300 or 400 perfect the Quick Masking goes fast. Just edge the out side with a small brush so it is nice and tight and then use a larger brush zoomed out to fill in. Don’t use the fill tool, you will get an edge between the fill and the brushed edge. Just paint it in. I have found very few things that I couldn’t mask out this way and quickly tool. A graphics tablet will make things faster, but a mouse works fine too.

R
R
Roberto
Jun 16, 2006
The problem with things like Magic Wand and Lasso is that they don’t came anywhere close to doing a good job, not without a lot of extra fine tuning work which can take more time than just using the Quick Mask mode and a brush.

R
AT
als_trash
Jun 16, 2006
I forgot to mention that, in the end, I’m only interested in getting the total area of these leaves. Thanks again to all who have replied!

allie
MV
My View
Jun 17, 2006
Also check out Advanced Masking tutorial (movie) at Russell Brown’s website along with a couple of other masking techniques at this site. http://www.russellbrown.com/tips_tech.html

wrote in message
I forgot to mention that, in the end, I’m only interested in getting the total area of these leaves. Thanks again to all who have replied!
allie
T
theartist
Jun 17, 2006
My View wrote:
Also check out Advanced Masking tutorial (movie) at Russell Brown’s website along with a couple of other masking techniques at this site. http://www.russellbrown.com/tips_tech.html

wrote in message

I forgot to mention that, in the end, I’m only interested in getting the total area of these leaves. Thanks again to all who have replied!
allie
I was looking all over adobe’s site for this one. I think it’s exactly what als_trash needs.
Thanks for the link; I bookmarked that puppy.

—
§¦: } theartist
AT
als_trash
Jun 19, 2006
Thanks for the tip. Good video. However, my problem remains that some of the colors I want to mask out are the same colors that I want to keep. Dodging and Burning aren’t going to do the trick for me. Channel Mixing doesn’t differentiate the areas I need differentiated, because the keep/drop colors, in the tight areas, are essentially the same. The real difference between the keep areas and the drop areas are that the keep areas are enclosed within circles of like colors, while drop areas are between those circles (not enclosed).

In the end, I’ve reconciled myself to do a first cut selection with a magic brush to get the general range of colors I’m looking for, then using a quick mask to fine tune that selection.

I still hold to my opinion that color differentiation married with edge detection/contour mapping algorithims should, in theory, be able to tackle this problem. Taking a look at a high-pass filtering of the image gives an idea of where one might start. But it’s something, apparently, yet to be developed. Thanks very much, everyone, for all your help. This has been interesting and educational.

Best,
Allie

theartist wrote:
My View wrote:
Also check out Advanced Masking tutorial (movie) at Russell Brown’s website along with a couple of other masking techniques at this site. http://www.russellbrown.com/tips_tech.html

wrote in message

I forgot to mention that, in the end, I’m only interested in getting the total area of these leaves. Thanks again to all who have replied!
allie
I was looking all over adobe’s site for this one. I think it’s exactly what als_trash needs.
Thanks for the link; I bookmarked that puppy.

—
§¦: } theartist
MV
My View
Jun 20, 2006
Any chance of adding a small jpeg of the image to your next reply so we can see exactly what you are after.

wrote in message
Thanks for the tip. Good video. However, my problem remains that some of the colors I want to mask out are the same colors that I want to keep. Dodging and Burning aren’t going to do the trick for me. Channel Mixing doesn’t differentiate the areas I need differentiated, because the keep/drop colors, in the tight areas, are essentially the same. The real difference between the keep areas and the drop areas are that the keep areas are enclosed within circles of like colors, while drop areas are between those circles (not enclosed).

In the end, I’ve reconciled myself to do a first cut selection with a magic brush to get the general range of colors I’m looking for, then using a quick mask to fine tune that selection.

I still hold to my opinion that color differentiation married with edge detection/contour mapping algorithims should, in theory, be able to tackle this problem. Taking a look at a high-pass filtering of the image gives an idea of where one might start. But it’s something, apparently, yet to be developed. Thanks very much, everyone, for all your help. This has been interesting and educational.

Best,
Allie

theartist wrote:
My View wrote:
Also check out Advanced Masking tutorial (movie) at Russell Brown’s website
along with a couple of other masking techniques at this site. http://www.russellbrown.com/tips_tech.html

wrote in message

I forgot to mention that, in the end, I’m only interested in getting the total area of these leaves. Thanks again to all who have replied!
allie
I was looking all over adobe’s site for this one. I think it’s exactly what als_trash needs.
Thanks for the link; I bookmarked that puppy.

—

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