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 04/05/2004 09:11:14 PM · #1
Fromthe advanced editing rules:

i]Your entry must come from a single photo, taken during the week of the challenge. No multi-image compositions, no layering of multiple exposures, no copying-and-pasting elements from other photographs (even those taken during the challenge week), etc.[/i]

Can we use a program like Image stacker to stack multiple time the same photo. I.E. For challenge i take multiple shots, only one of them have the good composition, subject, lighting etc but the photo is underexposed. Can I stack 5 copy of this image to simulate a longer exposure time?
 04/05/2004 09:38:06 PM · #2
I don't think you can do that.
 04/05/2004 09:39:21 PM · #3
Like different copies of the same image? Or different images taken at the same time?

1st - I think yes, it's like using layers
2nd - no, that's using multiple images
 04/05/2004 10:52:54 PM · #4
No multi-image compositions, no layering of multiple exposures, no copying-and-pasting elements from other photographs (even those taken during the challenge week), etc.

I think you posted your answer right before your question.
 04/05/2004 10:59:09 PM · #5
I believe "no layering of multiple exposures" refers to taking two versions of the same (static) shot using different exposures, and then stacking them to achieve a greater dynamic range than any single exposure could (similar to using a graduated ND filter).

I think if you are talking about taking a single photo, creating one or more duplicates of that same layer, and then stacking those, it should be within the rules (Advanced Editing set).
 04/05/2004 11:01:56 PM · #6
Yeah, the rules just say for MULTIPLE exposures. I believe you are talking about the exact same shot, just stacked, right? If that's the case, I think it would be legal to do.
 04/05/2004 11:52:23 PM · #7
this then brings into question shooting in RAW. setting a shadows exposure, then doing it again for a highlights exposure and stacking them in layers. that to me sounds like multiple images.
then, wouldn't that almost be the same if you made 2 layers of the same photo (whatever format) then adjusting the levels in each layer, one for highlights and another for shadows? leaving the layers in normal and then adjusting opacity to blend them. this is getting confusing. but it doesn't follow the rules for "adjustment" layer then does it?
 04/06/2004 09:48:35 AM · #8
Originally posted by dacrazyrn:
this then brings into question shooting in RAW. setting a shadows exposure, then doing it again for a highlights exposure and stacking them in layers. that to me sounds like multiple images.
then, wouldn't that almost be the same if you made 2 layers of the same photo (whatever format) then adjusting the levels in each layer, one for highlights and another for shadows? leaving the layers in normal and then adjusting opacity to blend them.

Creating a challenge entry from two RAWs at different exposures would be illegal, because you'd have to open two files in Photoshop and merge one into the other. That is not permitted. The second method you describe would be fine, because in Photoshop, you would only be using a single "source layer". That is the distinction we would use. The starting point for any submitted image has to be one group of pixel values from a single camera exposure. As long as it is only that exact set of pixel values that is used in an Advanced Editing entry, it is legal.

In other words, if we were to request proof and the editing steps used, in the first example we wouldn't be able to follow those steps and arrive at your exact picture without multiple source layers created from converting the RAW file multiple times. In the second example, we would be able to arrive at your picture using a single source layer. So the first would be DQ'd, the second not.
 04/06/2004 11:22:48 AM · #9
What i want to do is:

First i had this image:

wich i'd liked but there was something i didn't like about the exposure. I stacked 2 copy of THIS image (no mulitple exposure) together and it produced this image:


Would that be legal? the software used is images stacker
 04/06/2004 11:27:41 AM · #10
Does that not just give the same effect as brightness/contrast in photoshop?
 04/06/2004 11:32:40 AM · #11
Originally posted by Konador:
Does that not just give the same effect as brightness/contrast in photoshop?


Maybe but i took this photo 4 or 5 months ago and tried dozens of different technique in PS to get the best photo i can, sometime with good results sometime with poor results but the first time i tried to stack different copy of this image it gave me the best results in 3 minutes. I never succesfully achieved this quality in PS with that photo.
 04/06/2004 11:38:00 AM · #12
Well if you're using the same shot, it's legal under advanced editing :)
 04/06/2004 11:45:03 AM · #13
nicklevy, haven't you made changes to one (or both) of the stacked images before you merge them back into one?
 04/06/2004 12:13:08 PM · #14
Originally posted by coolhar:
nicklevy, haven't you made changes to one (or both) of the stacked images before you merge them back into one?


No changes! no level or contrast or anything. Just stacking.
 04/06/2004 01:18:23 PM · #15
I am not familiar with the Image Stacker program. Does it make changes for you perhaps? I can't seem to duplicate your results using PSP 7.
 04/06/2004 01:29:32 PM · #16
Originally posted by coolhar:
I am not familiar with the Image Stacker program. Does it make changes for you perhaps? I can't seem to duplicate your results using PSP 7.


If the photo you take is underexposed in any way there's no editing that can match image stacking because for every copy of the picture you stack it double the exposure. I.E. if you have a phot that is exposed for 1/90s and is underexposed, stacking 2 copy of your picture will transform your photo like if it was exposed for 1/45s instead of 1/90s. It's amazing
 04/06/2004 03:05:06 PM · #17
Originally posted by nicklevy:


If the photo you take is underexposed in any way there's no editing that can match image stacking because for every copy of the picture you stack it double the exposure. I.E. if you have a phot that is exposed for 1/90s and is underexposed, stacking 2 copy of your picture will transform your photo like if it was exposed for 1/45s instead of 1/90s. It's amazing


THere is way in PS where you can invert an image (like make it a negative) to make light areas dark and vice versa and then using some layer blending options lighten the dark areas up. If only i could remember where i read it...I tried it and it does bring out detail in the shadows without over lightening the highlights or adding noise as a levels adjustment tends to do if overdone.

chris

Ahh i found it - 'contrast masking' at luminous landscapes.
//www.luminous-landscape.com/tutorials/contrast_masking.shtml
04/06/2004 03:21:09 PM · #18
Originally posted by EddyG:

Creating a challenge entry from two RAWs at different exposures would be illegal, because you'd have to open two files in Photoshop and merge one into the other. .


How about creating a challenge entry from one RAW file, at two different exposures then layering and combining in photoshop ?
(Note ONE RAW file - one single in camera exposure)

What is the distinction between that and doing two 16 bit conversions, layering them and then applying different levels curves to the same image ?

The only difference is where and in which tool you combine the image and where and in which tool you vary the exposure.

The intent is obviously the same - you are using one exposure and different renditions of it to expand your dynamic range. But one method is legal and the other isn't just because of when you write parts of it to disk or not ?

Message edited by author 2004-04-06 15:21:45.
 04/06/2004 03:31:38 PM · #19
Originally posted by Gordon:
Originally posted by EddyG:

Creating a challenge entry from two RAWs at different exposures would be illegal, because you'd have to open two files in Photoshop and merge one into the other. .


How about creating a challenge entry from one RAW file, at two different exposures then layering and combining in photoshop ?
(Note ONE RAW file - one single in camera exposure)

Oops that is what I meant to type: "Creating a challenge entry from one RAW file as two different exposures would be illegal."

I'm not saying I agree with it; I actually pushed for allowing increased dynamic range via multiple identical exposures, but I conceded to the "single image" rule in order to make the Advanced Editing trial at least a reality. =]
 04/06/2004 03:33:40 PM · #20
Originally posted by EddyG:

I'm not saying I agree with it; I actually pushed for allowing increased dynamic range via multiple identical exposures, but I conceded to the "single image" rule in order to make the Advanced Editing trial at least a reality. =]


Mind you, as I typed it, because I can do a mid exposure, low contrast RAW convertion in 16 bit to photoshop, I can probably do pretty reasonable dynamic range adjustments anyway, within the rules. It requires 16 bit editing and layer support, but with CS that's all there now. Exposure adjustment up and down by a stop or 1.5EV or so should be okay with levels/ curves in 16 bit so no real need to convert it twice.
 04/06/2004 06:59:32 PM · #21
I think I agree with Gordon, that if you took a single RAW exposure, exported it with one setting, and then again with another setting, and then stacked those layers, it is just the same as taking a JPEG or TIFF original, duplicating the Background layer, and applying different adjustment layers.

The image still derives from a single set of pixels, and can be re-created from that one file plus enumerated software steps. If we are not going to allow it for RAW images, it makes no sense to allow any other stacking of multiple iterations of the same set of pixels either.
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