Turning white to black

[mark81]

Hi all,

So, I have done a load of sketching over the last year or so using black card and white pens. This has been fun and improved my observing, but I would much prefer to sketch on white paper with nice sharp pencils and then turn it into dark sky with white stars for a more professional finish.  Also adding a pitch black surround would be nice.  Is there an app for pc/android that anyone could recommend?

Thanks

Mark

 

[Dr_Ju_ju]

If you are using Windows, you can try the in-built MSPaint https://www.wikihow.com/Invert-Colours-in-MS-Paint 

[Mick J]

Also IrfanView has a Negative/invert option and a nice add border/frame option.  Windows, free and lots of other great options.

Edited March 15, 2020 by Mick J

[vlaiv]

Negative / invert makes issue with color.

If you want for example to keep actual color of stars in your sketches when processing them - there is simple way of doing that.

Here is example I made couple of years ago to show this effect:

Image is that of M82 - what I took with QHY5II color camera at the time (a bit of EEVA back then) and right is what it would look like if done on paper.

You can use Gimp to accomplish this (or any other program that can do color space transform). We will do it in one direction, but you can do it in opposite in the same way:

Open up image like this one:

Choose Colors / Components / Decompose and choose LAB color model.

Take L component and do Colors / Value invert and after that do Colors / Components / Recompose

This is result:

(here stars are black without color because they were saturated in original image - but in your drawing they should contain color if you draw them with appropriate color).

HTH

[mikeDnight]

I find it much easier sketching with graphite pencils, but then afterwards I'll use the edit function on my tablet to turn the pencil sketch into a negative. But as the pencil sketch is actually the real negative, using the negative function actually creates a positive, realistic view, which is much more pleasing.