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Shrinking really big files to postage stamp size...

A forum to post any lighthouse pictures you'd like others to see. Feel free to talk about lighthouse photography. Lighthouse-related photos (such as LSS and lenses) are also welcome.

Postby Gary Martin » Sun Sep 24, 2006 7:38 am


I had an e-mail from Kevin re the Sea Girt and first Hereford Inlet shots that I posted yesterday regarding the visual appearance of them. I wasn't terribly happy with either of them either...

Both started out as ~28 Mb BMP digital files (after filtering the TIFFs in Neat Image) that had to be shrunk down from 300 dpi/3872 pixels to 100 dpi/~650-700 pixels. I've been using Genuine Fractals 4.0 for quite a while and have generally been pretty happy with it, but I haven't been using it to shrink files quite that far in the past. I shoot nothing but RAW when I'm shooting digital, so there haven't been small sized jpeg's available to work form. That said, I'd like an opinion re the visual appearance of the following two files:

Version 1 - This was done with a 300 -> 100 dpi pitch reduction all in one shot followed by stepwise reduction in size using Genuine Fractals 4.0 as follows:

Step 1 in Genuine Fractals 300 dpi/3872 pixels -> 100 dpi/2400 pixels
Step 2 in GF 100 dpi/2400 -> 100 dpi/1200 pixels
Step 3 in GF 100 dpi/1200 -> 100 dpi/650 pixels

Image

Version 2 - This image was processed using successive reductions in pitch with only the attendant reduction in size associated with the change in pitch, i.e. 300 -> 240. The only manipulation in size was in the last step when the pitch was dropped to 100 dpi, a slight reduction in size was also made.

Step 1 in GF 300 dpi/3872 -> 240 dpi/3098 pixels
Step 2 in GF 240 dpi/3098 -> 200 dpi/2582 pixels
Step 3 in GF 200 dpi/2582 -> 160 dpi/2066 pixels
Step 4 in GF 160 dpi/2066 -> 100 dpi/650 pixels

Image

Quite often sharpening applied along the way has the nasty habit of giving objects in an image a "halo" around them. Neither of these images had any sharpening applied what-so-ever.

Personally, I'm not really happy with either but I thought I'd toss this out on the forum for people to comment on. It's interesting to note that the final BMP file, which is what I was working with does not show the haloing that appears in the jpeg. Then again, the BMP was an ~1.1 Mb file while the jpeg is about ~63 Kb.
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Postby Jen » Sun Sep 24, 2006 7:43 am


Gary, just for grins, try this. Open an edited, ready to downsize, file in Photoshop. Go to Image, Size, and reduce it to 800x600 and 72 DPI. Save it as a new file, and then try and post it. I'd be curious to see the comparison of that method to GF. You shouldn't have to go through a four step downsize process to post pix to the Web (IMHO).
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Postby Gary Martin » Sun Sep 24, 2006 7:47 am


Part of the culprit visually around the top of the tower may be the hand rail that you can see clearly in this unsharpened crop.

Image

This cropped segment is ~40 Kb so on this scale, the full image jpeg would probably be several undered Kb and too large to post on here.
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Postby Gary Martin » Sun Sep 24, 2006 7:53 am


OK, Jen, here it is...

The first step in PS takes you from 28.7 Mb to 961 Kb. This was then converted to a 63 Kb jpeg. IMO it's no better than using a multi-step reduction in GF.

Image

I think this one falls visually between version 1 and 2 above somewhere, but maybe that's just my eyes?
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Postby Hersh » Sun Sep 24, 2006 8:57 am


Without looking at them on screen side by side and really analyzing them, I don't see enough of a difference to warrant the 4 step processing in GF. All the images I post for web viewing are done with the basic resize in PSP. I don't bother with the GF, it's just too much hassle for me. Of course anything I'm going to print I take the extra time and do it up right, but not for web.

But that's just one guy's workflow.....
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Postby Gary Martin » Sun Sep 24, 2006 9:45 am


Seeing the minimal difference, I think I'm inclined to just say bahhhh humbug on doing it step-wise, shrink it once and be done with it.

Oh well, interesting exercise. I'm still waiting for Kevin to weigh in from Oz though since he made the query in an e-mail. I'd like to get his take on any difference in the three images on this thread.
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Postby Kevin vk2ce » Sun Sep 24, 2006 4:05 pm


Gary,

I can see very little difference between the 3 photos. My own uneducated guess is that it is something to do with the original photo when converting it to a jpg. I have noticed a similar problem with some of my scanned photos. I scan them at say 600 dpi and then save them as jpg's, the compression seems to do something sometimes and they come out with that ghosting effect similar to your 3 and yet others are crystal clear.
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