Sorry about that, I will try First please make sure you are saving a copy of your original scan. To convert to grayscale, Image > Mode > Grayscale. PS will comfirm you want to discard color information, click "yes" Levels- Image > Adjustments > Levels. Adjust the levels as shown above, but also play with the sliders a bit and observe what they do * When you are happy with the results hit ok. Now convert back to color : Image > Mode > RGB Color ( or CMYK Color or whatever fits your needs) Im guessing your artwork layer is locked and is called "Background" if so, double click it and it will become a regular layer. On the layers panel, to the left of the opacity, is the "transfer mode" dropdown. Select "multiply" and this will allow any colors on layers behind it, to show through, but preserve the line-art At this point you're good to go. Any new layers you create underneath the line art layer will show through. As far as the paper color you wanted to preserve, you have may options. You can use the eyedropper tool to select the color from the original, and fill a layer one solid color, you can use your original scan, by pasting it onto a layer, or there are many parchment and paper textures available via a google image search.
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