Sunday, May 29, 2011

How to Make Curtains from Panoramic Photographs

Click on image to enlarge
Last year I took a series of photographs at a fitness club for the ultimate purpose of making sun-blocking panels for windows in the cardio room.  The images on the panels would echo what the members were seeing when working out.

The above picture is a view of the panorama shot covering the largest window, and some single shots on the side windows.  It's an HDR image made from 5 exposures. I took it with a 15mm diagonal fisheye on my Canon 5D, and straighted the curvature in the vertical lines after the HDR processing using a photoshop plug-in by Image Trends, Inc., that's designed specifically to correct this kind of distortion created by fisheye lenses.

I won't get into how I photographed and stitched the panoramic image that became the sun-screen on the large window. That's a separate subject.  My challenge was figuring out how to cut the image up into panels and then blow them up to 24 inches wide to cover a window that's 219 inches (18.25 feet) long and 96 inches (8 feet) high.

This posting starts with the image captured, processed, and ready for conversion into curtain sized panels.

Here's the picture after I turned it into a black and white image, and before I cut it up.

Click on image to enlarge
Step 1 ... Make the Aspect Ratio Match the Window

I cropped the dimensions of this image to 6480x2880 pixels or 8x18 inches.  These dimensions are no accident. They give an almost perfect match to the aspect ratio of the window opening.  Converting the feet measurements of the window to inch measurements of the image worked well.

With dimension of 18.25x8 feet, the window's aspect ratio is 9.125x4. The picture has an aspect ration of 9x4.  Because the window is only 3 inches longer than nine 2ft panels will cover, I ignored the difference!  At most, there would be a negligible gap of less than a half inch between the panels.  Pulling them in slightly from the ends of the window would close the gaps to almost nothing. So I pretended the window had the exact same aspect ratio as the image.

The limiting factor in playing with the aspect ratio is the dimension of the media.  The panel fabric that will fit into my Epson 7900 printer is an even 24 inches wide. I didn't have the option of stretching the fabric.  If the widow were a little smaller than 18 feet, the material could be bunched up a bit to make the panels fit. Fortunately, the window didn't pose the more difficult problem of being too long for nine panels but too short for ten. I don't know what I would have done if I had a full 12 inches to make up for.  Possibly make a 10th panel and do a lot of bunching.

Step 2 ... Divide the Image into Equal Panels

The fabric is on rolls, but the rolls are 24 inches wide.  The 18+ foot window will need nine panels. Here is the description of how I divided the image into nine equal vertical segments, using an image with dimensions of 8x18 inches, and then blew the segments up into 2 feet x 8 feet for printing. Please post a comment if you have a better way.  I'm sure there's more than one way to do this, and I hope someone can improve on these instructions. 
  1. Open the image in Photoshop, and duplicate. Make a separate duplicate for each panel.  That would be 9 duplicates for this job.
  2. Work on the first duplicate image.  (Do not ever work on the original.)
  3. Check the image size by clicking on Image > Image Size.  In this example, this showed that this image has a width of 18 inches and a height of 8 inches. To make 9 panels, each panel will be 2 inches wide. Obviously, the dimensions will vary with the particular image and the project. We'll make the panels much larger to fit the widow's height later.  For now, just work with the sizes given.
  4. We will proceed from the left side of the panorama to the right, systematically, panel by panel.
  5. Click on the Crop button. Set the width and height to the correct dimensions.  For this image, I set the width to 2 inches and the height to 8 inches. Then drag the crop curser from the top left corner to the bottom edge.  This will create a panel exactly 2x8.  This is the first panel, and is the far left portion. 
  6. Now work on the second duplicate image.
  7. As we move inward for the remaining panels, it gets a little more complicated.  For the second panel, we need to set the width to 4 inches and remove the two inche panel on the far left as a second step.  So, set the width to 4 inches, and drag the crop curser from the top left corner as before.  Now, crop the cropped image you just made. On that cropped image, crop out a two inch panel from the right side by setting the crop button to a 2 inch width and 8 inch height, and drag from the top right corner of the 4x8 image. This will be the second panel.
  8. For the third panel, work on the third duplicate image. Set the width to 6 inches. Make the crop by dragging the crop curser from the top left corner as in the previous step. Then, crop the cropped image, once again setting the crop button to 2 by 8 and drag from the top right corner of the 6x8 image.
  9. Repeat these steps, using the remaining duplicates of the original image.  Increase the width of the crop by 2 more inches each time.  Then take a 2 inch panel from the right side of the crop.
  10. When all steps were finished, there were nine crops, in sequence from left to right, dimensionally 2 inches x 8 inches.  Be sure to save each crop.  I recommend re-naming each panel when the images are saved, giving them sequential numbers from 1 through 9 in this example.
Step 3 ... Resize Each Panel

The worst is over.  Resizing is easy compared to the task of cropping 9 separate panels. If you are bringing the images to a vendor to print them for you onto suitable fabric, just copy them onto a thumb drive or CD.  The vendor should know what to do to resize the image.  Using a resolution of 180 ppi would be fine for images this size.  Make sure the print is borderless, and a couple of inches of blank fabric are added at the top and bottom for hemming a pocket for dowels.  Dowels are the easiest way to hang these panels.

If you are printing the panels yourself, you have a wide format printer and know how to use it.  I won't repeat what you already know.  But here are some tips.  I import the images into Lightroom and do my output from there.  I always use Lightroom for my printing because I can easily batch the job, and the software will let me blow up the image, reformat it, choose a ppi that I want, and do the right output sharpening for the media I select. 

For this particular project, I used a paper backed flame resistant fabric that I purchased from Lexjet in Florida.  The paper backing lets the thin fabric move through the printer without binding or jamming.  I did not coat the material after printing because it was not going to hang in a place subject to abrasion.  I'd spray the material with one of many specialized laquers for this purpose if it were going on a roller or in a heavy traffic area.

As I mentioned above, the hardest thing about this project is getting the panels made.  After that, it's just like any other print job.

2 comments:

John midlton said...

It's a good idea to make a curtains from panoramic photos. It looks good in this picture view. I have take many photos in it on other things.

roman blinds

Michelle Smith said...

It's good to see this information in your post, i was looking the same but there was not any proper resource, thanks now i have the link which i was looking for my research
Curtains