Selecting Pixels of a Particular Color

Try using your Magic Wand with "contiguous" unchecked and a tolerance of zero. Make a tiny patch, just a pixel or two of the color you want to select (RGB value) and then click on it with the Magic Wand. It should select the tiny patch and every thing else that specific color.

I’m not sure if this will work 100% accurately, but it may.

Peadge 🙂

"stmx3" wrote in message

Given an image of randomly colored pixels, is it possible to select from the image only those pixels of a particular RGB color? I.e. can I specify (100,100,100) as my RGB value and select all pixels of that particular color?

-stmx3

stmx3 wrote:

Given an image of randomly colored pixels, is it possible to select from the image only those pixels of a particular RGB color? I.e. can I specify (100,100,100) as my RGB value and select all pixels of that particular color?

What is it you are trying to do?

—
John McWilliams

Yep, under Selection use "choose range" with zero tolerance. Don’t know if this is the right word, have the german Version.

Greetings
Bee Dee

"stmx3" schrieb im Newsbeitrag

Given an image of randomly colored pixels, is it possible to select from the image only those pixels of a particular RGB color? I.e. can I specify (100,100,100) as my RGB value and select all pixels of that particular color?

-stmx3

I’m trying to create a hidden message for an entry at geocaching.com. Basically, armed with a gps, people go looking for a cache in the woods at some coordinates. In this case, upon finding mine, hidden inside will be an RGB value. Given an image of random colors, by applying the correct RGB value they can then tease out the coordinates for another cache.

It’s all very fun, and in this case, gets them to delve into the uses of graphics software.

-stmx3

stmx3 wrote:

I’m trying to create a hidden message for an entry at geocaching.com. Basically, armed with a gps, people go looking for a cache in the woods at some coordinates. In this case, upon finding mine, hidden inside will be an RGB value. Given an image of random colors, by applying the correct RGB value they can then tease out the coordinates for another cache.

It’s all very fun, and in this case, gets them to delve into the uses of graphics software.

Whoa! That’s a helluva neat use. Peadge’s reply seemed to cover what I might have said- did that do it for you?

—
john mcwilliams

Given an image of randomly colored pixels, is it possible to select from the image only those pixels of a particular RGB color?

Yes. there are two ways to do it.

The clumsy way is to use the Magic Wand with a Tolerance value of 0, as long as the sample size is set to 1×1. (By default, when you click with the wand or eyedropper, it grabs the nearest pixels and averages hem.)

The easy way is to use the Select->Color Range command. That’s what it’s for.

—
Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

Thanks for everyone’s help. It sounds so easy now but I was really struggling to figure out a way with my old 5.0 LE version of the program. One of the driving issues will be the availability a program for all to download, whether it be an evaluation copy or not. But, it looks like the solution can be had fairly easily using the methods you’ve mentioned.

Again, thank you.
-stmx3

"Tacit" wrote in message

Given an image of randomly colored pixels, is it possible to select from the image only those pixels of a particular RGB color?

Yes. there are two ways to do it.

The clumsy way is to use the Magic Wand with a Tolerance value of 0, as

long as

the sample size is set to 1×1. (By default, when you click with the wand

or

eyedropper, it grabs the nearest pixels and averages hem.)
The easy way is to use the Select->Color Range command. That’s what it’s

for.

—
Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

Clumsy? In what way? Surely the Magic Wand Tool isn’t too heavy or awkward! 😉

It seems to be incredibly fast and quite accurate, the antithesis to "clumsy."

The Color Picker, on the other hand, can be a PITA, especially for someone new to the tool. Even a bit clumsy, perhaps.

Peadge 🙂

Clumsy? In what way? Surely the Magic Wand Tool isn’t too heavy or awkward! 😉

It seems to be incredibly fast and quite accurate, the antithesis to "clumsy."

The Magic Wand tool is clumsy because by default, it averages the colors it samples (which needs to be changed to select just one shade of color with perfect precision), because by default it selects contiguous colors only (which needs to be changed to select all of a given color), and by default it creates an antialiased selection. It also does not give visual feedback before creating the selection; if the selection doesn’t work out exactly right, you need to change the selection manually or adjust the Tolerance setting and try again.

Select->Color Range provides feedback about the selection it will make, allowing the user to change the tolerance of the selection interactively before making the selection. It also allows the user to set a tolerance for the selection and then include or exclude specific colors, again interactively, before creating the selection–something the Magic Wand doesn’t allow.

When I first started using Photoshop, back in 1992, I found myself using the Magic Wand often. Nowadays I touch the Magic Wand tool perhaps once a month, and I use Photoshop 30 hours a week. 🙂

—
Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

"Tacit" wrote in message

Clumsy? In what way? Surely the Magic Wand Tool isn’t too heavy or

awkward!

😉

It seems to be incredibly fast and quite accurate, the antithesis to "clumsy."

The Magic Wand tool is clumsy because by default, it averages the colors

it

samples (which needs to be changed to select just one shade of color with perfect precision), because by default it selects contiguous colors only

(which

needs to be changed to select all of a given color), and by default it

creates

an antialiased selection. It also does not give visual feedback before

creating

the selection; if the selection doesn’t work out exactly right, you need

to

change the selection manually or adjust the Tolerance setting and try

again.

Select->Color Range provides feedback about the selection it will make, allowing the user to change the tolerance of the selection interactively

before

making the selection. It also allows the user to set a tolerance for the selection and then include or exclude specific colors, again

interactively,

before creating the selection–something the Magic Wand doesn’t allow.
When I first started using Photoshop, back in 1992, I found myself using

the

Magic Wand often. Nowadays I touch the Magic Wand tool perhaps once a

month,

and I use Photoshop 30 hours a week. 🙂

—
Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

All good points, Tacit. The Color Picker does offer much more control and a far wider range of options. But in this case, where some of the OP’s geo-caching buddies, who may not be very familiar with Photoshop and might be forced to download a trial version of Photoshop or even Elements, the Magic Wand may prove to be far less of a challenge. But then challenge seems to be the intended goal! Regardless of which tool is used, the idea itself it quite fascinating. I sent it to some friends who geo-cache and they thought it was very cool. Thanks for the detailed response!

Peadge 🙂

Peadge wrote:

"Tacit" wrote in message

Clumsy? In what way? Surely the Magic Wand Tool isn’t too heavy or

awkward!

😉

It seems to be incredibly fast and quite accurate, the antithesis

to

"clumsy."

The Magic Wand tool is clumsy because by default, it averages the

colors

it

samples (which needs to be changed to select just one shade of

color with

perfect precision), because by default it selects contiguous colors

only

(which

needs to be changed to select all of a given color), and by default

it

creates

an antialiased selection. It also does not give visual feedback

before

creating

the selection; if the selection doesn’t work out exactly right, you

need

to

change the selection manually or adjust the Tolerance setting and

try

again.

Select->Color Range provides feedback about the selection it will

make,

allowing the user to change the tolerance of the selection

interactively

before

making the selection. It also allows the user to set a tolerance

for the

selection and then include or exclude specific colors, again

interactively,

before creating the selection–something the Magic Wand doesn’t

allow.

When I first started using Photoshop, back in 1992, I found myself

using

the

Magic Wand often. Nowadays I touch the Magic Wand tool perhaps once

a

month,

and I use Photoshop 30 hours a week. 🙂

—
Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

All good points, Tacit. The Color Picker does offer much more control

and a

far wider range of options. But in this case, where some of the OP’s geo-caching buddies, who may not be very familiar with Photoshop and

might

be forced to download a trial version of Photoshop or even Elements,

the

Magic Wand may prove to be far less of a challenge. But then

challenge

seems to be the intended goal! Regardless of which tool is used, the

idea

itself it quite fascinating. I sent it to some friends who geo-cache

and

they thought it was very cool. Thanks for the detailed response!
Peadge 🙂

That’s it exactly. You hit the nail on the head, Peadge. The users, if they don’t already have the program, must be able to download a trial version freely. The bigger the challenge, the better the puzzle. With limitations imposed by a free/trial version, I see the user as having to paint a swath of the given RGB onto the image and then, with the wand, select that color and all similar with tolerance set to zero, copy and past results onto a blank canvas, thereby revealing the "secret message".

My next step is to create a random image of "noisy" pixels…i.e. random colored pixels over the entire canvas. I would prefer to do that over selecting some image and discretely modifying
pixels…although this is the route I may end up taking.

-stmx3