On Tue, 2004-11-02 at 01:13 -0500, Tom wrote:

(new to gimp)

Welcome. :-)

Hi,

I would like to change the background color of a photo, (preferably with a gradient or shadow effect) but it's a single layer (jpg). I tried to 'select by color' and replace it, but the edges of the object in the foreground turn out jagged and looks bad. I also tried to invert the selection and cut and paste it into a new image file, but it looks just as bad.

Any ideas would be appreciated.

There are two tutorials about this at http://www.gimp.org/tutorials/ (in the "intermediate" section). As has been mentioned in another thread, the best technique varies a little depending on the type of image you are working with, but those two tutorials might give some starting points.

Cheers,
Malcolm

I would use the path tool to trace the outline of the bottle, then change the path to a selection. Then you can float the selection and put the layer on a different background. The path tool takes a bit of practice but I think it will produce the best results in this situation.

Tom wrote:

Thanks Eric. Here it is.

On Tuesday 02 November 2004 00:14, Eric Pierce wrote:

There are a billion different ways to do what you're talking about. But it really comes down to the quality/properties of the image you have.

Show us what you have.

On Tue, Nov 02, 2004 at 01:13:21AM -0500, Tom wrote:

(new to gimp)

Hi,

I would like to change the background color of a photo, (preferably with a gradient or shadow effect) but it's a single layer (jpg). I tried to 'select by color' and replace it, but the edges of the object in the foreground turn out jagged and looks bad. I also tried to invert the selection and cut and paste it into a new image file, but it looks just as bad.

Any ideas would be appreciated.

Thanks, Tom

(new to gimp)

Hi,

I would like to change the background color of a photo, (preferably with a gradient or shadow effect) but it's a single layer (jpg). I tried to 'select by color' and replace it, but the edges of the object in the foreground turn out jagged and looks bad. I also tried to invert the selection and cut and paste it into a new image file, but it looks just as bad.

Any ideas would be appreciated.

Thanks, Tom

On Tue, Nov 02, 2004 at 12:01:48PM -0500, Tom wrote:

I've been experimenting with all the suggested methods and getting various results. As far as making it trasnparent (how, when, why), I could use some advice. :)

the transparency is like an extra color that you can add called alpha. jpegs dont like it and you will have to remove this extra color before you can save your image as a jpeg again. This extra color can be added while working with gimp on this image with no problem.

There are a few different ways to add this extra transparent color.

From the menu, -->Layer -->Transparency -->Add Alpha Channel.

or from the Layer Dialog, right click next to the thumbnail and select Add Alpha Channel.

To remove the alpha channel so you can save as a jpeg again, -->Image -->Flatten Image. This will cause any transparent areas to be filled in by the background color you can see on the gimp toolbox.

carol

Thanks Carol, Mark and Malcolm.

I've been experimenting with all the suggested methods and getting various results. As far as making it trasnparent (how, when, why), I could use some advice. :)

On Tuesday 02 November 2004 02:31, you wrote:

hello,

On Tue, Nov 02, 2004 at 01:54:19AM -0500, Tom wrote:

Thanks Eric. Here it is.

On Tuesday 02 November 2004 00:14, Eric Pierce wrote:

There are a billion different ways to do what you're talking about. But it really comes down to the quality/properties of the image you have.

Show us what you have.

On Tue, Nov 02, 2004 at 01:13:21AM -0500, Tom wrote:

(new to gimp)

you are not the only one new to gimp ....

I would like to change the background color of a photo, (preferably with a gradient or shadow effect) but it's a single layer (jpg). I tried to 'select by color' and replace it, but the edges of the object in the foreground turn out jagged and looks bad. I also tried to invert the selection and cut and paste it into a new image file, but it looks just as bad.

Any ideas would be appreciated.

sounds like you are handling the image fine, you just need to take a few more steps with it. because the background is almost all of the same color, selecting by color or contiguous color areas is the quickest. (that is what you did). additionally, under the Selection menu is "Feather". this option takes away the jaggies.

you figured out how to make it transparent?

carol

tfox777@earthlink.net (2004-11-02 at 0154.19 -0500):

Thanks Eric. Here it is.

Ok, I used select by colour, clicking first at the top area, then clicking with shift key more times and a bit lower until it selected all but the bottle and some of the white reflection in front.

sides selected
v v

##
##
/##\
####
####

Then zoom in and finish by hand the reflection, if you have clicked enough times, down a bit each time, you should have it easy, because the lower edge of the bottle is dark and should have been cut for you (the ==== part in the graphic).

Play with feather, grow/shrink or quickmask if you need to adjust the selection, until happy. Finally apply the colour with the bucket tool, using Colour mode for example and adjusting tranparency on the tool options. That way you get a similar gradient, keeping the reflection.

Another way is that once the selection looks ok, instead of using the bucket, add a layer, use the selection to build a layer mask, and fill the full layer. This is a bit more complex, but lets you change colour quickly (save the selection to channel as security measure, then remove selection and drag and drop to the image window from selector as many times as you want) and mode and transparency on the fly.

IOW, concepts you should input into a search engine for deeper explanations: quickmask, selection, layer mask, layer mode (plus gimp tutorial with each of them).

GSR