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Post by octavius on May 30, 2022 14:18:44 GMT
Hi folks, My intention is to scan all my trade pages to my Google drive and provide a link to members interested in trading (when I've qualified). For example, here is a jpg of one of my trade pages - it has a small file size (0.26 MB) but zooming in is not possible because the quality deteriorates badly. Saving as a png file (124 MB) allows zooming in to determine if it is of acceptable quality but can everyone open up a png? 0.26 MB jpg: 124 MB png file:
Cheers!
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philatelia
Member 
Captain Jack - my best kiloware find ever!
Posts: 3,655
What I collect: Ireland, Japan, Scandy, USA, Venezuela, Vatican, Bermuda, Austria
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Post by philatelia on May 30, 2022 14:51:19 GMT
No problems viewing with my iPad, so anyone using any IOS device should be good to go. Image was nice and sharp, too!
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brightonpete
Departed
Rest in Peace
On a hike at Goodrich-Loomis
Posts: 5,110 
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Post by brightonpete on May 30, 2022 15:25:40 GMT
A page scanned at 300 DPI should be good enough to zoom in and check. Saves on bandwidth if some need to watch that. JPG's are so much smaller, especially when saved at a lesser quality. No need to save at best quality there!
Just my opinion...
Peter
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banknoteguy
Member
Posts: 324
What I collect: 19th Century US, High denomination US (> $1), 19th century covers US, Indian Feudatory States and most recently I acquired a BigBlue [with about 5,000 stamps] and pristine pages.
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Post by banknoteguy on May 30, 2022 16:23:36 GMT
I think all browsers handle both jpg and png image formats (and more besides those two).
PNG is what is known as a lossless compression format. You specify a compression factor when creating a PNG file but higher compression factors do not produce any loss of resolution. It just takes longer to compress and decompress (and the compression is not nearly as much as with a JPG). I use JPG unless someone/somesite needs a specific format. You will find that PNG produces files about 10X bigger than jpeg at similar resolutions using a PNG compression factor of 9 [max].
JPG on the other hand is a lossy format which means that during compression the image file created will get a lot smaller but also lose resolution. I use 75% as the standard I use for JPG compression. Some people say you should use 77%. I can't tell the difference for anything above 75%. So I use that.
I find that to zoom in to see the detail, I want to see, I need to scan at 600dpi at least. I scan all my stamps at 1200dpi but covers usually at 600dpi. 1200dpi images take up a lot of space even with a 75% JPG compression factor. And you have to scale them down to include with a posting here.
Here is a link to a page scanned at 300, 600 and 1200 dpi using an Epson scanner and GIMP, stored as JPGs with a 75% compression factor and the 300 & 600 dpi images as PNGs with a 9 compression factor:
I should note the file sizes 300dpi.jpg 1.2M, 600dpi.jpg 5.5M, 1200dpi.jpg 22.9M, 300dpi.png 12M, 600dpi.png 55M, the 1200dpi.png would have been about 230M.
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Post by octavius on May 30, 2022 18:31:15 GMT
philatelia, brightonpete and banknoteguy,
Many thanks for the replies and advice.
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vikingeck
Member
Posts: 3,551
What I collect: Samoa, Tobacco theme, Mail in Wartime, anything odd and unusual!
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Post by vikingeck on May 30, 2022 19:34:36 GMT
Just to say banknoteguy ‘s 300jpg is perfectly good for me. If I was a buyer I would find the image more than adequate. |
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tobben63
Member
Stamp eat sleep repeat
Posts: 1,874
What I collect: I collect to much, world wide!
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Post by tobben63 on May 30, 2022 19:48:23 GMT
I would prefer the 600dpi jpg. But the 1200 on banknoteguy page is awesome. |
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Post by octavius on May 30, 2022 22:29:36 GMT
Fair enough guys. Many thanks for the advice.
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angore
Member
Posts: 5,699
What I collect: WW, focus on British Empire
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Post by angore on May 31, 2022 10:32:17 GMT
I downloaded the file and does not look like a 300dpi image. Image hosts will compress them. I do lots of scanning a 100 and 300 dpi and it looks closer to a 100dpi as POSTED. I am not saying it was scanned at 100dpi.
My 300dpi scans (what I scan all album pages) yields a 1.8 MB file 2544x3296. 8.5-inches x 300 = 2550.
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Post by octavius on May 31, 2022 11:33:53 GMT
Image hosts will compress them. Never thought of that. Thanks for pointing it out to me |
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banknoteguy
Member
Posts: 324
What I collect: 19th Century US, High denomination US (> $1), 19th century covers US, Indian Feudatory States and most recently I acquired a BigBlue [with about 5,000 stamps] and pristine pages.
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Post by banknoteguy on May 31, 2022 12:33:12 GMT
Angore said,
What file did you download? The one I made? Or?
Your 300dpi scan yields a 1.8M file at what JPG compression setting?
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jdtrue66
Member
Inactive
Posts: 287
What I collect: US&US FDC, Keys & Locks, NUDES, Rubber Ducks, USS NJ covers
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Post by jdtrue66 on May 31, 2022 12:33:22 GMT
You would have a harder time finding a person who could not view PNG then finding one who could. PNG was developed in response to GIF being copyright protected. Since it is a free to use format everyone has built in viewers. All webbrousers unless they are ment to be just text viewers and those would still read the Alt tag. All ofice and publishing programs read it along with most photo editing software.
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angore
Member
Posts: 5,699
What I collect: WW, focus on British Empire
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Post by angore on May 31, 2022 15:34:47 GMT
I misread 128 MB as kB. It was early. I was looking at the image on imgbb and not the other file. I scan at 300 dpi at Quality set at 100 (Vuescan) so least compression for jpg. For forum posts, I will scan at 100 dpi or resize my 300 dpi scans to 800 wide pixels. I am at work so cannot access my scans to check range. I rechecked some recent scans and the file size varies from 1,6 MB (the title page for the country) to 4.4MB for a scan of a Vario page. The folder has 25 scans.  |
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