OhLook THREAD STARTER Spiderwoman  16,404 posts Gallery: 68 photos Best ofs: 2 Likes: 3403 Joined Dec 2012 Location: California: SF Bay Area More info | I don't see a difference, either, but I also have a 15" screen.  HOSTED PHOTO please log in to view hosted photos in full size. And can someone tell me how to find the amount of compression? PRONOUN ADVISORY: OhLook is a she. | A FEW CORRECT SPELLINGS: lens, aperture, amateur, hobbyist, per se, raccoon, whoa, more so (2 wds.), shoo-in | IMAGE EDITING OK
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Pippan Senior Member  More info Post edited 3 months ago by Pippan. | To my eyes and on a 5K iMac screen, the AMASS reduced version looks slightly sharper and more detailed. Nevertheless I think it's time I started using the CS5 Photoshop I've had on my computer for years and been too over-awed to try. — Please feel free to offer your thoughts on how I might improve my images —
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Dec 27, 2017 03:02 | #48 And can someone tell me how to find the amount of compression? Do you have Photoshop Elements? In File > Save for Web, you can see before and after resizing. Mostly I use this program for to resize for internet, but Canon's DPP can resize too: in File > Convert and save you can resize very well, although you can't see how big (MB's) the photo will be.
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tzalman Fatal attraction.  13,403 posts Likes: 169 Joined Apr 2005 Location: Gesher Haziv, Israel More info | And can someone tell me how to find the amount of compression? In general, when photographers who aren’t complete nerds (like me) talk about jpg compression, they are referring to it in an imprecise way as being “high” or “low” because the photo editing programs they use have an interface that while giving them a choice of “Quality” settings, represent the amount of compression being applied only indirectly. The amount of compression is inverse to the “Quality” – a high Quality setting uses less compression and a low Quality setting uses more compression in order to achieve a smaller file size while sacrificing quality. And different programs use different “Quality” scales; Photoshop uses 0 – 12 while Lightroom uses the same 13 Adobe compression algorithms but they are represented by a crazy 0 – 100 scale. DPP uses 1 – 10. (I don’t know Preview, but I wouldn’t touch any program that doesn’t give the user some control over jpg quality vs. compression.) The subject is further complicated by the fact that the amount of compression done at a given setting is also influenced by the photo’s content. Large areas of solid or near solid color, like blue skies, compress well, but highly detailed photos and highly sharpened images are less amenable to compression. Also, image noise cannot be differentiated from image detail, so in general, as ISO goes up, compression goes down and file size increases. To really know, in hard numbers, the amount of compression that has been done to a given jpg photo file, you have to know its uncompressed size. There is a simple formula for that: [Pixels X 3] / 1.048 = MB. The explanation: Pixels is the total number of pixels in the image, height times width. Each of those pixels contains three color values (Red, Green, Blue) and in jpgs those values are always written in 8 bits. 8 bits equal 1 byte, so each of the three color values equals 1 byte of data. Pixels times 3 gives the total image content in bytes. 1024 bytes are a kilobyte and 1024 kilobytes are a megabyte (MB), so dividing twice by 1.024 or once by 1.024 squared (1.048576) gives the answer in MB. Dividing the uncompressed size by the jpg size, gives the amount of compression. Elie / אלי
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LevinadeRuijter I'm a bloody goody two-shoes!  17,590 posts Gallery: 256 photos Best ofs: 10 Likes: 5271 Joined Sep 2008 Location: Amsterdam, The Netherlands More info | Dec 27, 2017 09:50 | #50 OhLook, I took your two 1280px versions to Photoshop and blew them up to have a better look. The AMASS version clearly has the edge. But the Preview version after some sharpening is right up there. Here is the comparison. Blown up to 500%. Left the Preview version, in the middle the AMASS version, right the Preview version after some sharpening.  HOSTED PHOTO please log in to view hosted photos in full size. Levina
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Dec 27, 2017 09:58 | #51 Like many have said never let a website resize your images. Upload to the size you want to display. Learn about the 3 phases of sharpening.  HOSTED PHOTO please log in to view hosted photos in full size.  HOSTED PHOTO please log in to view hosted photos in full size. Image Editing OK
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Dec 27, 2017 10:00 | #52 PPI has no effect on screen viewing. 1st image is set to 1. Next image 1000  HOSTED PHOTO please log in to view hosted photos in full size.  HOSTED PHOTO please log in to view hosted photos in full size. Image Editing OK
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Dec 27, 2017 10:41 | #53 Have you tried using Canon's DPP? I found the resizing algorithms have improved over the years. I think the sharpening on the basic image adjustment window defaults to 3 which is pretty good. Try 4 and it starts to get aggressive at 5. The File - Convert and Save command offers pixel dimensions. Image Editing OK
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JohnSheehy Goldmember 2,287 posts Likes: 243 Joined Jan 2010 More info | Dec 27, 2017 10:50 | #54 digital paradise wrote in post #18527185  PPI has no effect on screen viewing. 1st image is set to 1. Next image 1000 Hosted photo: posted by digital paradise in ./showthread.php?p=18527185&i=i253720085 forum: RAW, Post Processing & Printing Hosted photo: posted by digital paradise in ./showthread.php?p=18527185&i=i122056249 forum: RAW, Post Processing & Printing Good thing the first one doesn't automatically print for you when you look at the post.
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PhotosGuy Moderator  More info | Dec 27, 2017 11:11 | #55 digital paradise wrote in post #18527181 Hosted photo: posted by digital paradise in ./showthread.php?p=18527181&i=i115440898 forum: RAW, Post Processing & Printing Hosted photo: posted by digital paradise in ./showthread.php?p=18527181&i=i63303048 forum: RAW, Post Processing & Printing Interesting that the crop looks sharper & with more detail than the original image. FrankC - 20D, RAW, Manual everything...
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Dec 27, 2017 11:26 | #56 PhotosGuy wrote in post #18527221 Interesting that the crop looks sharper & with more detail than the original image. No PP with the original. Image Editing OK
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JohnSheehy Goldmember 2,287 posts Likes: 243 Joined Jan 2010 More info | Dec 27, 2017 13:41 | #57 PhotosGuy wrote in post #18527221 Interesting that the crop looks sharper & with more detail than the original image. That's pretty common when the downsampling method does not include a lot of sharpening. A downsample can be all over the map, sharpness-wise, with the same original image. Upsampled images, too, can have ramped or splined transients between original pixels, or just duplicate them and maintain pixel contrast.
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Pekka El General Moderator  More info | Dec 27, 2017 14:16 | #58 Some comments on this: The Forum Boss, El General Moderator
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digitalparadise Cream of the Crop  More info Post edited 3 months ago by digital paradise. | Dec 27, 2017 15:56 | #59 John Sheehy wrote in post #18527342 That's pretty common when the downsampling method does not include a lot of sharpening. A downsample can be all over the map, sharpness-wise, with the same original image. Upsampled images, too, can have ramped or splined transients between original pixels, or just duplicate them and maintain pixel contrast. True and the algorithms have really improved over the last 10 years. Image Editing OK
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