Posted: Wed Sep 26, 2007 12:37 pm
This was fun
Bringing out the texture is basically increasing the slope of the L channel.
Several curves were tried with the most successful being that used in Example-03-SS 4,5 and 6.
The same L curve was used in these three images.
In Example-03-SS 1 I tried to increase the texture by increasing the slope of all channels. It became my benchmark for gauging subsequent attempts.
In Example-03-SS 2 I tried inverting channels a and b which gave interesting results. In hindsight maybe inverting only one channel would be worth pursuing.
Example-03-SS 3 is again a fairly basic adjustment.
Example-03-SS 4 had no adjustment to the a or b channels. It set the L curve for the next 2 images
The little flattening of the curve around 70 allowed the other parts of the curve to be steepened. It did however have a slight decrease in contrast in certain areas but these areas were narrow stripes near those dominant light petal edges and each side of those stripes benefited from increased contrast. As there were more pixels each side of the effected areas there was a perceived improvement when this adjustment was made.
However, this works for this image at this size/resolution and may or may not for others.
Example-03-SS 5 changed the slope of the b channel so that the slope was steeper and that inpot less than 50 was output as less than zero and subsiquently blue. In effect about half of the yellow pixels were turned blue. I was hoping that this would result in some added colour contrast which would be perceived as enhanced texture.
Example-03-SS 6 used the same L channel curve and a standard b channel curve and experimented with the a channel
In conclusion, the texture is mainly in the L channel. If it's not there it doesn't matter what you do in the other channels.
regards
Bringing out the texture is basically increasing the slope of the L channel.
Several curves were tried with the most successful being that used in Example-03-SS 4,5 and 6.
The same L curve was used in these three images.
In Example-03-SS 1 I tried to increase the texture by increasing the slope of all channels. It became my benchmark for gauging subsequent attempts.
In Example-03-SS 2 I tried inverting channels a and b which gave interesting results. In hindsight maybe inverting only one channel would be worth pursuing.
Example-03-SS 3 is again a fairly basic adjustment.
Example-03-SS 4 had no adjustment to the a or b channels. It set the L curve for the next 2 images
The little flattening of the curve around 70 allowed the other parts of the curve to be steepened. It did however have a slight decrease in contrast in certain areas but these areas were narrow stripes near those dominant light petal edges and each side of those stripes benefited from increased contrast. As there were more pixels each side of the effected areas there was a perceived improvement when this adjustment was made.
However, this works for this image at this size/resolution and may or may not for others.
Example-03-SS 5 changed the slope of the b channel so that the slope was steeper and that inpot less than 50 was output as less than zero and subsiquently blue. In effect about half of the yellow pixels were turned blue. I was hoping that this would result in some added colour contrast which would be perceived as enhanced texture.
Example-03-SS 6 used the same L channel curve and a standard b channel curve and experimented with the a channel
In conclusion, the texture is mainly in the L channel. If it's not there it doesn't matter what you do in the other channels.
regards