Post Reply 

finding the edge

Jan 20, 2012, 03:52 (This post was last modified: Jan 20, 2012 04:03 by banksiaman.)
Post: #1
finding the edge
First post hope I get it right.
as an example using a earlier post "Changing a white background to transparent (.png)"
I have zoomed part of the edge of the logo.It varies from white thru grey then up to the logo colour.
My Query how do you decide at what point in this change do you stop the transparent section?
As when you put colours or pictures as a background you would I think have to reblend the edges for each type of background.


Attached File(s) Thumbnail(s)
       
Find all posts by this user
Quote this message in a reply
Jan 20, 2012, 07:37
Post: #2
RE: finding the edge
I wrote a short explanation here: http://gimpforums.com/thread-proper-subj...d-painting

Now answering your questions on
https://Gimp-Forum.net
Visit this user's website Find all posts by this user
Quote this message in a reply
Jan 20, 2012, 09:26
Post: #3
RE: finding the edge
Thanks ofnuts.I actually found your post while searching around and came back here to say so ( am still digesting it) .
I have been playing around with gimp for a couple of weeks. ITS BIG. but lots of fun.
Find all posts by this user
Quote this message in a reply
Jan 20, 2012, 09:50
Post: #4
RE: finding the edge
I tried to be exhaustive but short. If there are glaring holes in my explanations, just say so Smile

Now answering your questions on
https://Gimp-Forum.net
Visit this user's website Find all posts by this user
Quote this message in a reply
Jan 20, 2012, 23:37
Post: #5
RE: finding the edge
No it covered what I needed to know from go to finish.
What I did misunderstand was "[grow the selection by 2 pixels] in theChanging a white background to transparent "
I thought it was referring to the threshold and it wasnt till I looked at the "proper selection post" that I realised Selection > grow where a seperate item on the window menu.
The wide field GIMP covers gives me a steep learning curve but I love it rather than pressing a auto button
my next " finding the edge task "is to extract the board and people from the attached pic
I think "The canonical way is to use Color/Color to alpha and give the background color" is the way to go


Attached File(s) Thumbnail(s)
   
Find all posts by this user
Quote this message in a reply
Jan 21, 2012, 01:35
Post: #6
RE: finding the edge
(Jan 20, 2012 23:37)banksiaman Wrote:  No it covered what I needed to know from go to finish.
What I did misunderstand was "[grow the selection by 2 pixels] in theChanging a white background to transparent "
I thought it was referring to the threshold and it wasnt till I looked at the "proper selection post" that I realised Selection > grow where a seperate item on the window menu.
The wide field GIMP covers gives me a steep learning curve but I love it rather than pressing a auto button
my next " finding the edge task "is to extract the board and people from the attached pic
I think "The canonical way is to use Color/Color to alpha and give the background color" is the way to go
The "color-to-alpha" way is OK with logos because it recovers the anti-aliasing pixels. But on a "natural" image there are no such pixels and other techniques should be used. On that picture I would go a with a clipping path, plus some specific surgery for the hairs.

Now answering your questions on
https://Gimp-Forum.net
Visit this user's website Find all posts by this user
Quote this message in a reply
Jan 21, 2012, 06:21 (This post was last modified: Jan 21, 2012 06:24 by banksiaman.)
Post: #7
RE: finding the edge
Thanks ofnut from what you say does this sound the way to go
from Wiki
A clipping path (or "deep etch"[1]) is a closed vector path, or shape, used to cut out a 2D image in image editing software.
the clipping path references I find in GIMP are a bit confusing.
The basics in brief seem to be

make a mask channel,
add layer mask to picture channel and copy in mask
add alpha to picture channel and you are home.

For the MASK
The path tool would be used for the major part of the subject making all transparent except the area around the hair (i.e a clipping path)
The area around the hair will have to be done by making the this area gray scale and hopefully making the hair strands white to light gray and the ocean black
Find all posts by this user
Quote this message in a reply
Jan 21, 2012, 09:34 (This post was last modified: Jan 21, 2012 09:35 by ofnuts.)
Post: #8
RE: finding the edge
Not really...what you describe is the "mask" technique. Basically:

- You add an alpha-channel if there isn't one
- You add a layer mask filled with white (all opaque)
- By painting on the mask, you decide what you keep: white to keep, black to make transparent, gray for intermediate stuff. The nice thing is that you can change you mind at any time by painting with the opposite color. More or less the erase on steroids.
- Use with hard brush for most of background, soft brush around subject
- Much easier with a graphics tablet.

The clipping path is done with either the Path editor (Path) or with the scissors (Iscissors), and used to create a selection when done. Works well when there are regular lines (cars, trains, planes, buildings....) but should still be OK on on your picture.

You can combine several methods on the same image, for the image at hand: path for the boat and paddles, scissors for the characters, and some automatically generated mask for some of the hair.

Now answering your questions on
https://Gimp-Forum.net
Visit this user's website Find all posts by this user
Quote this message in a reply
Jan 23, 2012, 10:57
Post: #9
RE: finding the edge
Thanks for the help ofnuts.
As I said steep learning curve.Had to do a lot of practice on tools to get this far,but am now getting to terms with some of them

I used scissors as it went well with the canoe
used scissors and paths for much of the body,
had trouble with the paddle silver part used smudge to cleanup.

with the head used mask method from
http://gimpchat.com/viewtopic.php?f=24&t...14&start=0
I have read afew tuts on masks
all seem to go same way make black/white mask
add mask to picture
clean up
have attached my cutout
Once again thanks for answeing my questions it was a big help


Attached File(s) Thumbnail(s)
   
Find all posts by this user
Quote this message in a reply
Jan 23, 2012, 13:40
Post: #10
RE: finding the edge
Some more work required Smile

- Still a lot of left-overs on the background, especially around the head (to get rid of them: do a free-hand selection around subject, rather close, invert selection, and delete).
- Lots of smudge around paddle on the right. When using paths you just need a straight line there.
- Left shoulder/hand/foot of mother
- If you put a dark layer as a background, you'll also notice part of her left knee has become transparent. Or you were using them as shark bait Smile
- The cleaner you get the cut out, the easier it will be for everything else later.

Also, crop the image, no need to carry the overhead of a 10Mpix picture when you subject is about 1Mpix.

Now answering your questions on
https://Gimp-Forum.net
Visit this user's website Find all posts by this user
Quote this message in a reply
Jan 24, 2012, 10:02
Post: #11
RE: finding the edge
    lol sprung I was telling everybody what a great job I had done.Lucky I didnt zoom and put a black background.
Have now cleaned it up learn a lot each time I do it I discover something like cleaning up the paddle
what I did was used path for a selection around the original copied it
went to the layer that had the wonky paddle on it used the selection to rub out all that was crook then pasted in the original.
Then cut the paddle out properly .
Find all posts by this user
Quote this message in a reply
Post Reply 


Possibly Related Threads...
Thread: Author Replies: Views: Last Post
  Hard Edge Painting sgreeny12 2 80 Nov 15, 2017 23:48
Last Post: sgreeny12
  transparent background with smooth edge Sagemode 2 822 May 1, 2014 15:42
Last Post: Sagemode
  Straightening an edge in a photo humanguy 5 713 Nov 2, 2013 22:55
Last Post: ofnuts
  Fade Edge on Pic with Transparency kenizl86 1 463 Jul 11, 2013 16:46
Last Post: ofnuts
Sad Hard Edge Hinum 5 1,601 Apr 7, 2013 01:22
Last Post: ofnuts

Forum Jump:


GIMP ForumPortalArchiveContactTermsRSS