Adding text to a RAW

pigeonhill

1155

Adding text to a RAW

« on: 12 / October / 2023, 18:01:00 »

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@reyalp

I’m sure I’ve asked you this before, so forgive me if I have.

Is there a way to add a text string to an image?

My use case is to add text to the first and last images of a bracket set, ie the bookends of a bracket set.

The two images with text on them need not be RAWs, ie they could be DNGs or JPEGs, but when ingested into Lightroom, say, I would wish them to be displayed contiguously with my bracket set RAWs.

Cheers

Garry

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reyalp

14082

Re: Adding text to a RAW

« Reply #1 on: 12 / October / 2023, 19:15:18 »

You can modify the raw image data before it's saved or a jpeg is created using rawop https://chdk.fandom.com/wiki/Lua/Raw_Hook_Operations

There is currently no functions for drawing text, so you'd have to roll your own with set_pixel.

Providing a way to re-use CHDK fonts was on my list of things to add some day, but I'm not sure anyone other than me has ever used this feature, so I haven't felt much need to add enhancements...

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pigeonhill

1155

Re: Adding text to a RAW

« Reply #2 on: 13 / October / 2023, 02:20:04 »

Many thanks for the info, I’ll certainly be looking to exploit being able to draw coloured rectangles.

As I said, my use case is to enable the functionality in my scripts to record info on my bracketing info, which can be complex, eg

Dark Frame to differentiate start of overall bracketing set
Bracket focus set
Dark Frame to differentiate start of simulated ND bracketing set at infinity
ND bracket set
Dark Frame to differentiate end of ND bracket set
Dark Fran to differentiate end of overall bracketing set

At least, if things work out, I should be able to add colour to add info to the dark frames.

Ideally I would like to add text info to a dark frame, eg capturing the info in the bracket set. This will be especially useful when I’m exposure and ND bracketing with a manual lens, ie limited EXIF data.

Cheers

Garry

« Last Edit: 13 / October / 2023, 02:23:14 by pigeonhill »

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reyalp

14082

Re: Adding text to a RAW

« Reply #3 on: 13 / October / 2023, 03:29:53 »

Quote from: pigeonhill on 13 / October / 2023, 02:20:04

Many thanks for the info, I’ll certainly be looking to exploit being able to draw coloured rectangles.

Yes, if you can use simple shapes (like green square = start, red = end or whatever) as indicators, you wouldn't have write a whole text rendering system. If you can live with just numbers, something akin to a seven segment display could also be a useful intermediate option.

CHDK/SCRIPTS/TEST/rawdraw.lua gives an example of the required hook setup and drawing functions.

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