Colouring a scanned pdf picture

[adam_b2019]

Hi, 

I have scanned some hand drawn black and white pictures and saved them as PDF files. I am colouring them in using GIMP with a view to have them printed as greeting cards. 

When bucket filling in areas there is an outline of 3 to 4 pixels that haven't been filled. They are a mixture of grey tones. I'm assuming this because the drawing was done using an ink pen and has then been scanned. 

I'm having to use the pencil tool in GIMP to fill in the outline around each coloured area...it's incredibly time consuming. Is there any way to select pixels that are all of the same colour then change them to white? Or can anyone think of a solution?

Thank you

[Blighty]

Without seeing an example image this is a bit of guess.

Assuming your scan is black lines on a white background. Well, almost white background.

1. Use Colors > Brightness-Contrast to increase the contrast.

2. Use Colors > Color to Alpha to make the white transparent. For Color to Alpha to work you need 2 things: Image must be RGB; there must be an alpha channel.

3. Create a new transparent layer below the original image.

4. In the layers dialogue, select the original image layer.

5. Use the selection tools to make a selection on area to be coloured.

6. Select > Grow by a suitable amount, probably 3 to 4 pixels.

7. In the layers dialogue select the new, lower transparent layer.

8. On this layer bucket fill the selection.

[adam_b2019]

(03-14-2019, 10:02 AM)Blighty Wrote: Without seeing an example image this is a bit of guess.

Assuming your scan is black lines on a white background. Well, almost white background.

1. Use Colors > Brightness-Contrast to increase the contrast.

2. Use Colors > Color to Alpha to make the white transparent. For Color to Alpha to work you need 2 things: Image must be RGB; there must be an alpha channel.

3. Create a new transparent layer below the original image.

4. In the layers dialogue, select the original image layer.

5. Use the selection tools to make a selection on area to be coloured.

6. Select > Grow by a suitable amount, probably 3 to 4 pixels.

7. In the layers dialogue select the new, lower transparent layer.

8. On this layer bucket fill the selection.

Thanks for this!

Yes, it's black on a white background. Increasing the contrast makes it look sharper which is great. I've used 'Select > Grow' which works really well. 

Honestly, I got confused by the process of adding a transparent layer. I couldn't do it. Total newbie here...your instructions are clear so it's my bad. What is the advantage of creating a new layer as opposed to just using the grow function on the image? I'll be saving it as a PDF and exporting it if that makes any difference.

[Blighty]

(03-15-2019, 07:46 PM)adam_b2019 Wrote: Honestly, I got confused by the process of adding a transparent layer. I couldn't do it. Total newbie here...your instructions are clear so it's my bad. What is the advantage of creating a new layer as opposed to just using the grow function on the image? I'll be saving it as a PDF and exporting it if that makes any difference.

To create a new layer below your image:
1. Select the Layers Dialogue
2. There is a button "Create a new layer" - select the "Transparency" option
3.The new layer is created above your image. Use the down arrow to move it below your image.

Why use a new transparent layer?
If you just use the Grow option on the image layer and then bucket fill - the colours will damage your black lines. If you bucket fill the colours on the layer below the black lines then the lines are not affected at all. The black lines will be above the colours. Experiment and see the difference. Remember that you can use Undo.

[adam_b2019]

(03-16-2019, 05:44 AM)Blighty Wrote:

(03-15-2019, 07:46 PM)adam_b2019 Wrote: Honestly, I got confused by the process of adding a transparent layer. I couldn't do it. Total newbie here...your instructions are clear so it's my bad. What is the advantage of creating a new layer as opposed to just using the grow function on the image? I'll be saving it as a PDF and exporting it if that makes any difference.

To create a new layer below your image:
1. Select the Layers Dialogue
2. There is a button "Create a new layer" - select the "Transparency" option
3.The new layer is created above your image. Use the down arrow to move it below your image.

Why use a new transparent layer?
If you just use the Grow option on the image layer and then bucket fill - the colours will damage your black lines. If you bucket fill the colours on the layer below the black lines then the lines are not affected at all. The black lines will be above the colours. Experiment and see the difference. Remember that you can use Undo.

Thank you, I'll have a play around with it! That's really helpful, I'm grateful