On 8/6/07, Rei Shinozuka wrote:

is there a (relatively) simple way to add a "galen rowell" filter. that's the late national geographic photographer to made great use out of graduated color filters to bring out the colors in sunset, etc.

If you're using a digital camera: Maybe if you use RAW format. otherwise: no, by the time you have scanned in the film it is already too late (GR filter effects the perception of the camera)

Anyway, it's probably better to use an HDR tool rather than GIMP, since GIMP is currently limited to 8bit and so isn't a very good choice for manipulating RAW images.

these sky colors are often become washed out due to overexposure necessary to expose the darked earth-based objects.

thanks,

-rei

-- Rei Shinozuka shino@panix.com
Ridgewood, New Jersey

On 8/6/07, Rei Shinozuka wrote:

is there a (relatively) simple way to add a "galen rowell" filter. that's the late national geographic photographer to made great use out of graduated color filters to bring out the colors in sunset,

David Gowers writes:

otherwise: no, by the time you have scanned in the film it is already too late (GR filter effects the perception of the camera)

Anyway, it's probably better to use an HDR tool rather than GIMP,

Sure, that's probably better; but with a lot of images you can bring out much more vibrant color simply by using tools like brightness/ contrast, levels or curves, or by overlaying the image with itself and playing with layer modes.

So to get a graduated filter effect, try making a duplicate layer with a layer mask, then draw a black/white gradient on the layer mask. Then you can operate on just the sky part using the various brightness tools.

You could also use a graduated selection (e.g. draw a gradient on the quickmask), but if you use a separate layer with a layer mask you can change the "graduated filter" after the fact, making it more gradual, or lower, or cutting out that tree sticking up above the horizon, or whatever other editing you need, without losing the contrast effect you've already done on the sky.

David Gowers wrote:

If you're using a digital camera: Maybe if you use RAW format. otherwise: no, by the time you have scanned in the film it is already too late (GR filter effects the perception of the camera)

True, but there are workarounds...

If the scene is relatively static (like a landscape), try taking a couple of shots at different exposures (one for the sky, one for the ground) and combine them in Gimp.