Jump to content


Photo

Can someone with a CAD program assist me?

  • Please log in to reply
12 replies to this topic

#1 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12535
  • Joined: 01 Feb 2006

Posted 11 April 2013 - 11:05 AM

I want to do some drawings that show how contrat is affected on extended images based on how the diameter of the Airy Disk of a star decreases with aperture.

To do this, I need to have pictues of the Airy Disk images I am attaching (I can email the original file) that have a transparent background.

The idea is to use some blown up images of planets and show how the Airy Disks from the smaller apeture spreads the energy from any geometric point on the extended target to a further distance than with a larger aperure.

To do that, I want to use Airy Disks images with a transparent background rathar than a black background so that the Airy Disk and the rings can be super-imposed over the background image.

Does anyone have a program that can convert these Airy Disk images so that any area in each frame that is black will be converted to being transparent?

Thanks in advance...

Agian, if you need the original image, just PM me your email address and I can send it to you, and then you will have my address to return it.

Again, thanks....

Attached Files



#2 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 43566
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 11 April 2013 - 12:12 PM

Eddgie:

I think such a venture would be worthwhile. Generating a planetary image by summing the disks and diffraction rings could be informative. I am not sure you need a Cad program for this, Cad programs generally are vector based and have minimal image handling capabilities.

But if you want to give it a try, there is a program called Draftsight which is a free 2-D CAD program made by Dassault Systemes, Dassault's main product is Solid Works which is a very popular and powerful 3-D modeling program, Draftsight seems to be also a serious and capable program.

Jon

#3 HunterofPhotons

HunterofPhotons

    Apollo

  • -----
  • Posts: 1062
  • Joined: 26 Apr 2008
  • Loc: Rhode Island, USA

Posted 11 April 2013 - 02:43 PM

Do you have PhotoShop?

dan k.

#4 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12535
  • Joined: 01 Feb 2006

Posted 11 April 2013 - 04:17 PM

Thanks for the encouragement.

I will look into the software. If it is free, I can at least try it.

I am hoping there is such a thing as a "Transparent" fill, where I can select the black background and convert it to transparent.

I could never do the entire planet, but what I though I would do would be to blow up a picture of Jupiter and scale some small feature on it (like a low contrast festoon) so that I could super-impose the diffraction patterns directly on to the image at the right scale, so that people could see how the size of the diffraction pattern determines how contrast can be lowered over a very large angular area due only to the size of the diffraction pattern of a small aperture.

I realize that it would only be an aproximation of what is happening, but it would hopefully convey an understanding of why contrast transfer increses with aperture.

Thanks again. Will see if I can find it and make it work.

#5 Eddgie

Eddgie

    Voyager 1

  • *****
  • Posts: 12535
  • Joined: 01 Feb 2006

Posted 11 April 2013 - 04:18 PM

Sorry, I do not.

Do you know if this function is available in Photoshop? I have a neighbor that is a professional photographer and I know he has the program...

#6 Pinbout

Pinbout

    Cosmos

  • *****
  • Posts: 7585
  • Joined: 22 Feb 2010
  • Loc: nj

Posted 11 April 2013 - 05:51 PM

You have to play with the transparency maps for the layers in photoshop. Change it from normal to multiply or screen or overlay. Cad won't do what you want.

#7 GlennLeDrew

GlennLeDrew

    Voyager 1

  • *****
  • Posts: 10572
  • Joined: 17 Jun 2008
  • Loc: Ottawa, Ontario, Canada

Posted 11 April 2013 - 05:59 PM

Indeed, this is all about rasterized images, which Photoshop or the open source 'equivalent', GIMP, handles with panache.

And a very useful project I heartily endorse.

#8 Pinbout

Pinbout

    Cosmos

  • *****
  • Posts: 7585
  • Joined: 22 Feb 2010
  • Loc: nj

Posted 11 April 2013 - 09:07 PM

here's your image as a screen transparency over top of jupiter

Attached Files



#9 HunterofPhotons

HunterofPhotons

    Apollo

  • -----
  • Posts: 1062
  • Joined: 26 Apr 2008
  • Loc: Rhode Island, USA

Posted 12 April 2013 - 10:58 AM

You have to play with the transparency maps for the layers in photoshop. Change it from normal to multiply or screen or overlay.....


What Danny said.
As with most procedures in PhotoShop there are several paths to the same goal. You can also select the areas you want to make transparent with the magic wand or some such, and under 'Help' select 'export as transparent image'. This may only be available for 8-bit images.

dan k.

#10 oo_void

oo_void

    Viking 1

  • *****
  • Posts: 588
  • Joined: 13 Nov 2009
  • Loc: San Francisco, CA

Posted 12 April 2013 - 12:51 PM

Though there is cost associated with it ($300) and a learning curve, but if you have any coding aptitude, writing some custom functions in PixInsight would be great for experiments like this.

#11 GlennLeDrew

GlennLeDrew

    Voyager 1

  • *****
  • Posts: 10572
  • Joined: 17 Jun 2008
  • Loc: Ottawa, Ontario, Canada

Posted 13 April 2013 - 11:20 AM

Edggie,
I'm curious to know if Danny's efforts here have proved helpful. This thread is otherwise hanging in limbo...

#12 Crow Haven

Crow Haven

    Apollo

  • -----
  • Posts: 1309
  • Joined: 09 Jan 2009
  • Loc: Oregon USA

Posted 13 April 2013 - 04:33 PM

Another way to create the airy discs is to construct the pattern with Photoshop Elements (the cheaper $70 program) on a transparent background and save the file as a .png file that can then be brought into any photo manipulating program you have that can handle .png files as well as .jpg files. There you can add your jpg planet image and then overlay the airy disc png file, scale it to whatever size you want, enhance its opacity, etc. and save the final image as a jpg.

I played with this idea using the first of your airy discs and drew in Photoshop Elements one that seems close. The attached image is of the transparent airy disc png file overlaying a colored bkg for example.
---Maya

Attached Files



#13 Crow Haven

Crow Haven

    Apollo

  • -----
  • Posts: 1309
  • Joined: 09 Jan 2009
  • Loc: Oregon USA

Posted 13 April 2013 - 04:37 PM

Here is the .png file image -- it probably won't show up well as the background is transparent and the airy disc is in shades of white...but it can be copied from this post and saved as a .png. If not, and if you or anyone wants the file I can email it.

Attached Files








Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics