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Author Topic: Auto cropping digital photographs of 35mm slides?  (Read 1582 times)

earlybird

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Auto cropping digital photographs of 35mm slides?
« on: May 12, 2019, 11:05:47 am »

Hi,
 I have assembled a rig to photograph 35mm slides with a macro lens. I am framing the exposure to include a bit of the frame.

 I am wondering what sort of options may exist for automatically cropping to the edge of the frame. I primarily use Adobe Camera RAW and Photoshop CS6, but am open to other solutions.

 What would you suggest?

 Thank you.
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earlybird

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #1 on: May 12, 2019, 11:29:29 am »

FWIW,
 I just discovered that a function such as I am searching for has existed within Photoshop for a while under Menu: File > Automate > Crop and Straighten Photos so I tried it and it does exactly what it says, but it does not account for slight variations in skew so the results are not as refined as that which you might produce if you used Photoshop's perspective crop tool with special care.

 I am hoping for something that automates a function similar to the perspective function as I am already doing my best to frame the copy and seem to equal the results of the  Menu: File > Automate > Crop and Straighten Photos by simply cropping with the viewfinder.

 I seem to recall one company had an application that was intended to automatically "tilt-shifted" architecture shots, but I can't remember what it is.
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kirkt

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #2 on: May 12, 2019, 11:33:06 am »

Does your version of ACR support the upright (Auto perspective) tool?  Maybe run through that first and then auto crop.

Kirk
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earlybird

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #3 on: May 12, 2019, 12:14:38 pm »

Hi,
 Thank you for the suggestion. I am using ACR 9.1.1 and do not see that option. My version of ACR does have a manual "auto straighten" tool that is very helpful, but time consuming.

 Thank you.
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digitaldog

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #4 on: May 12, 2019, 12:37:57 pm »

Have you tried the "Trim" command in Photoshop?
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earlybird

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #5 on: May 12, 2019, 10:06:41 pm »

The Menu: Image > Trim command seems to offer results that are similar, yet still different, from the Menu: File > Automate > Crop and Straighten Photos command.

The Trim command does does not seem to address the occasional need to straighten or make edges parallel and congruent.

Here are examples of Trim and Crop and Straighten Photos:

« Last Edit: May 12, 2019, 10:10:18 pm by earlybird »
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TonyW

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #6 on: May 13, 2019, 05:39:34 am »

The Menu: Image > Trim command seems to offer results that are similar, yet still different, from the Menu: File > Automate > Crop and Straighten Photos command.

The Trim command does does not seem to address the occasional need to straighten or make edges parallel and congruent.

Here are examples of Trim and Crop and Straighten Photos:
The Automate > Crop and Straighten tool, as you have found out, has its limitations and requires that sides be parallel in the x, y planes and the corner lines in those plane perpendicular, not a parallelogram.
Quick illustration of Automate C&S.  Top dealing with an image that complies with the parallel and perpendicular rules but is just skewed, C&S does a credible job.  Bottom images converging verticals confuses but still it manages to find the top and bottom parallel lines.

I believe the problem really lies in your 'rig' not being parallel in x and y axis, or the placement of slides leads to slight keystoning which automate C&S will not cure. 

If the slide image contains really noticeable horizontal or vertical planes and those planes are parallel to the sides of the slide mount then why not just crop in camera to eliminate slide edges and eliminate the need to C&S in post?

Otherwise, you may find the Perspective Warp is your friend if it is available in your PS version, but of course, just a manual solution as you have to select corners before pressing the Auto icon
« Last Edit: May 13, 2019, 06:18:59 am by TonyW »
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earlybird

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #7 on: May 13, 2019, 09:24:53 am »


Thank you for noting the 'problem' with my 'rig'. I believe you are correct about the cause of the non parallel edges. Although my "rig" is not currently assembled in its final iteration, I anticipate that I will face limitations with regards to precision of assembly, so I am asking about post processing possibilities.

I do not want to crop out the slides' edges with camera positioning because I consider the ideal to be a circumstance where a small sliver of the slide edge remains in the frame of the final output to both document and emphasize that the slide has been copied in its entirety.

After I find an automated method to select a boundary for cropping I hope to find an automated solution to "expand" the selection by some number of pixels to include a border of the slide's frame. I would like the frames to appear consistently spaced in the final output. In my opinion, that would be an ideal circumstance.

I looked into recent versions of Adobe Camera RAW's Auto Perspective, (Thank you to kirkT for the helpful suggestion). It seemed like an excellent collection of processes, but it seems like a solution that is only available as a rental. I would like to purchase a perpetual solution. 

I hope the fact that I do not know of an automated solution, does not mean that someone does know of an automated solution.


Thank you.





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earlybird

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #8 on: May 14, 2019, 08:16:35 am »

Is it possible that DXO Viewpoint may be able to automate the procedure?

I attempted a trial last night but realize that I ran a trial of it 2 years ago on the same computer and can not run another trial now that I have a more focued interest in its capabilities.

Thank you.
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TonyW

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #9 on: May 14, 2019, 09:56:06 am »

Is it possible that DXO Viewpoint may be able to automate the procedure?...
No, not if you wish to comply with your previously stated requirements of an automated software system correcting skew, convergence/divergence, cropping to include whole area then uncropping to reveal a sliver of slide mount.

I am curious so do you actually have a typical copy of a slide you have shot (assuming that the images posted thus far are not what you are shooting) that you can post here or link to?

Best Advice - Get it right in camera first.  Adjust your rig before the shoot to be parallel to the sensor in all planes.  Easy enough to print a grid pattern on transparent material and mount in a slide frame then line up on camera LCD.  Once set and locked down shoot away.

If you are not able to guarantee your rig accuracy and as you seem to be open to spending money even the cheapest slide copy attachment should give you good results with square to sensor accuracy.  Spend a little more for sophistication a bellows copy unit, a Bowens illumitran or a colour enlarger with head inverted camera mounted to rail.






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earlybird

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #10 on: May 14, 2019, 07:25:41 pm »

Will Viewpoint work to automatically to correct non parallel edges and crop to those edges?

I would consider 1 out of 2 better than 0.
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earlybird

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #11 on: May 14, 2019, 08:30:18 pm »

FWIW,
 I just downloaded one of the very common iPhone "scanner" apps and made a photocopy of a 35mm slide with purposefully skewed framing edges . The app automatically found the corners of the image, and with one click it cropped the frame to those edges.

 The process seemed to work really well, which encourages my hope that a similar automatic cropping capability exists for desktop PC use.

 Thank you.
« Last Edit: May 14, 2019, 08:34:21 pm by earlybird »
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earlybird

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Re: Auto cropping digital photographs of 35mm slides?
« Reply #12 on: May 20, 2019, 09:55:19 am »

Hi,
 In lieu of getting a second chance at a trial of DXO Viewpoint 3, I have been corresponding with their support to learn how the automated corrections work. The apparent answer to my question is that the automated corrections only apply to distortion corrections made by correlating their lens database with your photographs' EXIF listings.

 The other tools, particularly the one that is similar to Photoshop's perspective crop, are similar to Photoshop's perspective crop and evidently require manual placement of the corners.

 Thank you.
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