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#51
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thumbnail sizes
On 1/7/2018 10:12 PM, Savageduck wrote:
snip ...but why the need for thumbnails in the first place, or have I missed something? Several reasons: 1. They can be used when thumb tacks take up too much space; 2. They are sturdier than thumb tacks -- PeterN |
#52
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thumbnail sizes
On 1/8/2018 1:26 PM, nospam wrote:
In article , Alfred Molon wrote: I have been doing this digital photography thing for some time, and I have yet to have the need to produce a thumbnail of any quality. If you have your own web photo gallery site, you can use ImageMagick to produce the thumbnails for the pages (I do so). you 'can', but only if you want to do it the hard way. numerous apps can automatically create thumbnails and links to the full size images simply by exporting a web site, and in a variety of layouts. And there is not one word of scripting, or line of code in any of them. -- PeterN |
#53
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thumbnail sizes
In article , PeterN
wrote: I have been doing this digital photography thing for some time, and I have yet to have the need to produce a thumbnail of any quality. If you have your own web photo gallery site, you can use ImageMagick to produce the thumbnails for the pages (I do so). you 'can', but only if you want to do it the hard way. numerous apps can automatically create thumbnails and links to the full size images simply by exporting a web site, and in a variety of layouts. And there is not one word of scripting, or line of code in any of them. correct. |
#54
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thumbnail sizes
In article , "Mayayana"
writes: | I've been using this to make thumbnails of jpeg files: | | for img in *.JPG; do | echo thumbnailing $img | convert -geometry 105x70 $img $img | done | Are people supposed to know what OS/software you're using that code with? No, but it shouldn't be necessary to get the gist of the above. I wonder why you don't just extract the thumbnails when possible. Don't your cameras create them in the JPGs? It should be quicker and yield better quality images. Maybe they do; I don't know. How can I check. For the same size, why should they be better quality? |
#55
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thumbnail sizes
In article , "Carlos E.R."
writes: On 2018-01-07 23:30, Mayayana wrote: "Phillip Helbig (undress to reply)" wrote | I've been using this to make thumbnails of jpeg files: | | for img in *.JPG; do | echo thumbnailing $img | convert -geometry 105x70 $img $img | done | | Files from the K10D result in thumbnails of about 57 kB and those from | the GR of about 46 kB, with little variation. Is there a simple | explanation as to why? | | The K10D is 10 megapixels and the GR 16, but I don't see why that is | relevant here, but maybe I am missing something. | Are the originals the same aspect ratio? If not then you might be getting something like a 105x65 and a 105x50. You also didn't spec the compression level with the quality parameter. (Assuming you're using ImageMagick as Carlos speculated.) Oh, I'm more than 95% certain :-) Aspect ratio is the same. |
#56
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thumbnail sizes
In article .com,
Savageduck writes: I am still baffled as why these thumbnails have to be produced in the first place. A proof/contact sheet, some sort of project, what? To put them on a web page which loads fast with links to higher-resolution images. I didn't mention that because I don't see why it's relevant. Yes, different cameras, but same aspect ratio. Yes, the contents of the photos are different, but the difference in file size depending on content is much less than the difference between the two cameras. JPEG quality is certainly not exactly the same for the high-resolution images. |
#57
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thumbnail sizes
In article , "Carlos E.R."
writes: Maybe he wants to have a directory that loads and browses fast with small versions of the photos. Who knows? Right. For instance, somebody I knew generated them in order to create a web page on his home server. Right. The user would see a bunch of photos, click on one and get the large version. Right. So he wanted to generate much smaller versions to optimize load time for the preview. Right. Yeah, sure, there will be some product out there that does it all. Where is the joy in it, instead of doing it yourself completely? Or maybe he was creating one of those "products" :-P The script will produce thumbnails of an arbitrarily large number of files. I have another script which produces a complete web page. I type two commands and it is done. The quality of the thumbnails is not an issue. Between the lines, there are some suggestions that some cameras might somehow include a thumbnail in the JPEG image, which could perhaps be extracted with less effort than creating a new one with my script. If so, that would be interesting to know. Out of curiosity, the question about the different sizes of the thumbnail files remains, though. |
#58
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thumbnail sizes
In article , Phillip Helbig (undress to
reply) wrote: I am still baffled as why these thumbnails have to be produced in the first place. A proof/contact sheet, some sort of project, what? To put them on a web page which loads fast with links to higher-resolution images. I didn't mention that because I don't see why it's relevant. it's very relevant. you're doing things the hard way. with the proper software, it's a couple of clicks to export a complete web page (even uploading it to your server), including thumbnails, links to full size images and in whatever layout you want. the computer is there to do work *for* you. |
#59
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thumbnail sizes
"Phillip Helbig (undress to reply)" wrote
| Are the originals the same aspect ratio? | If not then you might be getting something | like a 105x65 and a 105x50. You also didn't | spec the compression level with the quality | parameter. (Assuming you're using ImageMagick | as Carlos speculated.) | | Oh, I'm more than 95% certain :-) | | Aspect ratio is the same. | Then the only other thing I can think of is that the cameras are saving at different quality levels and IM is copying them. Their docs say that's what it tries to do: Set quality at the same level as it was saved when possible. You could test it by setting the quality. That might be a good idea, anyway. If the camera saved at, say, 90, then IM is going to save a 90 version of a 90. You can also just check the quality setting of the cameras, or the resulting photos. Many viewers will show the quality level of the last save. I wrote myself a VBScript to extract thumbnails. I also wrote an HTA (using an Internet Explorer window) to show images as thumbnails and click one to view it larger. That won't do you any good on Linux, but the idea might be adaptable if you're doing this locally. It wasn't clear to me whether you're dynamically loading them to view on your computer or just creating them once for a website. If it's local, you may not need to resize at all. IE (and presumably other browsers) is amazingly fast and efficient at resizing for display. If you generate a webpage with: IMG SRC="D:\bigpic.jpg" WDITH=105 HEIGHT=70 you can very quickly generate a thumbnail sheet dynamically from full-size images. Of course you wouldn't want to do it that way online because it would be slow and your visitors would need to download the big version. In case it's useful, here's the thumbnail extractor package: http://www.jsware.net/jsware/scrfiles.php5#jpginf It could probably run in WINE. You just drop a folder onto it and all available thumbnails are extracted. But I wouldn't bee surprised if there's a Linux tool to do the same thing. And here's the thumbnail viewer: http://www.jsware.net/jsware/scrfiles.php5#picview Sample pics he http://www.jsware.net/jsware/linkpics/tview1a.jpg http://www.jsware.net/jsware/linkpics/tview2.jpg |
#60
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thumbnail sizes
In article , "Mayayana"
writes: Then the only other thing I can think of is that the cameras are saving at different quality levels and IM is copying them. Their docs say that's what it tries to do: Set quality at the same level as it was saved when possible. You could test it by setting the quality. That might be a good idea, anyway. If the camera saved at, say, 90, then IM is going to save a 90 version of a 90. You can also just check the quality setting of the cameras, or the resulting photos. Many viewers will show the quality level of the last save. OK. At first glance, it seems that the smaller thumbnail files are from the camera with higher-quality JPEGs. If it's local, you may not need to resize at all. IE (and presumably other browsers) is amazingly fast and efficient at resizing for display. If you generate a webpage with: IMG SRC="D:\bigpic.jpg" WDITH=105 HEIGHT=70 you can very quickly generate a thumbnail sheet dynamically from full-size images. Of course you wouldn't want to do it that way online because it would be slow and your visitors would need to download the big version. Right. In case it's useful, here's the thumbnail extractor package: http://www.jsware.net/jsware/scrfiles.php5#jpginf It could probably run in WINE. You just drop a folder onto it and all available thumbnails are extracted. But I wouldn't bee surprised if there's a Linux tool to do the same thing. Does this imply that the JPEG files already contain thumbnails? |
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