thumbnail sizes
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. |
thumbnail sizes
"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 | Are people supposed to know what OS/software you're using that code with? 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. |
thumbnail sizes
On 2018-01-07 21:46, 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 | Are people supposed to know what OS/software you're using that code with? Linux/bash and ImageMagick, obviously :-P 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. To customize the size and quality, for instance. -- Cheers, Carlos. |
thumbnail sizes
On 2018-01-07 21:07, 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. I was going to say that the camera with more megapixels would convert to a bigger size, but the reverse is happening. -- Cheers, Carlos. |
thumbnail sizes
On Jan 7, 2018, Phillip Helbig (undress to reply wrote
(in article ): 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 Why? Why not use decent software? 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? Different cameras, different image content. 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. The RAW file size, and native JPEG size is going to be different for those two cameras. As a result any thumbnail from those different sources is going to have a different size. I am still curious as to why you need to generate thumbnails. It seems to be a pointless exercise. -- Regards, Savageduck |
thumbnail sizes
On Jan 7, 2018, Carlos E.R. wrote
(in article ): On 2018-01-07 21:46, Mayayana wrote: "Phillip Helbig (undress to 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 Are people supposed to know what OS/software you're using that code with? Linux/bash and ImageMagick, obviously :-P That figures. 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. To customize the size and quality, for instance. Quality for thumbnails? To what purpose? It seems to be a waste of time, and a futile, unnecessary exercise. -- Regards, Savageduck |
thumbnail sizes
"Carlos E.R." wrote
| I was going to say that the camera with more megapixels would convert to | a bigger size, but the reverse is happening. | MP doesn't matter because it's the same number of pixels in the thumbnail if they're both the same width/height. There could be slight differences due to simpler or more complex images that compress differently, but with such a big difference the only explanation I can think of is that there's a difference in the compression. The code doesn't include a "quality" parameter to set compression level so maybe ImageMagick is deciding based on input size? Who knows? He's using a hammer to hit a tack. It's hard to see why it should matter. He's using a limited command line tool to get thumbnails and not even setting the quality option. Does he really need exactly that size? If so, why? Is it worth sacrificing quality? He didn't explain any of that. Apparently he doesn't care very much about the quality but is just curious about the different file sizes resulting. |
thumbnail sizes
"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.) You didn't say what the context of the code is. You didn't say why you're making thumbnails or whether they need to be the same size. You didn't extract them, which would probably make more sense. So all we know is that you're making thumbnails with a poorly suited tool and you don't much care about the quality of them. But you do care about the file size? Why? It'd be easier for people to provide a helpful answer if you'd explain yourself. We're not your mother. |
thumbnail sizes
On 2018-01-07 22:26, Savageduck wrote:
On Jan 7, 2018, Carlos E.R. wrote (in article ): On 2018-01-07 21:46, Mayayana wrote: "Phillip Helbig (undress to 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 Are people supposed to know what OS/software you're using that code with? Linux/bash and ImageMagick, obviously :-P That figures. 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. To customize the size and quality, for instance. Quality for thumbnails? To what purpose? It seems to be a waste of time, and a futile, unnecessary exercise. No. I said "to customize the size and quality" which is different than doing a quality thumbnail. ie, to have thumbnails of the exact quality (small quality) that one wishes. -- Cheers, Carlos. |
thumbnail sizes
On 2018-01-07 22:22, Savageduck wrote:
On Jan 7, 2018, Phillip Helbig (undress to reply wrote (in article ): 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 Why? Why not use decent software? "convert" is very decent and powerful software. What would you use in a script, then? -- Cheers, Carlos. |
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