Photobucket

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Ralph
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Re: Photobucket

Post by Ralph »

Caultron wrote:When you reduce the size of an image, the editing program has to "average" multiple pixels into one. It's like creating a smaller version of a tile mosaic. So that introduces some degradation as well.
Don't lossless formats like PNG resolve that problem? Obviously that means they aren't quite as efficient, space-saving-wise, as JPG but I think it's a good compromise between lossy compression and full-size uncompressed formats.
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Re: Photobucket

Post by Stevie D »

crfriend wrote: Stevie -- Those shots of Whitby are gorgeous, especially the ones in the late afternoon light. Magic!
Missed this earlier. :oops:
Thanks Carl! :)
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Stevie D
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Re: Photobucket

Post by Stevie D »

Ralph wrote:Don't lossless formats like PNG resolve that problem? Obviously that means they aren't quite as efficient, space-saving-wise, as JPG but I think it's a good compromise between lossy compression and full-size uncompressed formats.
Yes, PNG format is a very good compromise. It's also possible to edit and save PNG files with little (if any) degradation of the image.
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crfriend
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Re: Photobucket

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Ralph wrote:Don't lossless formats like PNG resolve that [re-sampling] problem? Obviously that means they aren't quite as efficient, space-saving-wise, as JPG but I think it's a good compromise between lossy compression and full-size uncompressed formats.
Nope. PNG does solve some of the compression issues because it's lossless, but nothing can mitigate the inevitable damage done when an image taken at one resolution is resized (scaled) to another.

Standards like PNG, JPEG, and GIF are storage formats; they're how a digital image in a computer's memory gets stored on disk. Some of these use no compression at all (e.g. RAW), some only optionally do (e.g. TIFF), some, to save space, quantise the colour-gamut (e.g. GIF), and others allow one to specify the level of compression applied to the image (e.g. JPEG). Ideally, with imaging, and any other technology that samples and analogue signal to produce a digital replica, "more is better" (i.e. more samples per unit (with unit being time for audio and unit being area for imagery) than less -- up to a point where the difference between the replica and the original analogue signal is imperceptible.

JPEG, especially, was designed taking into account human physiology and perception factors. This can make it difficult to see the "compression artefacts" left behind by the process, but they are there. The easiest way to see these is to overzoom (magnify up beyond the native resolution) and look for tiles "tiles" in which JPEG does its work. By digging into those at high magnification, one can "see" the algorithm at work.

As with other signal-processing mechanisms, be they analogue or digital, degradation of signal quality multiples over generations. This is why a copy of a cassette tape sounds worse than the original cassette which, in turn sounded worse than the original source album. This is why if one is working in either audio or video (for that is what still photography has become) that one only use either no compression (if one has the space) or lossless compression (which exacts a toll in time). Even very high-quality JPEG compression becomes very apparent after more than a few generations.
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Judah14
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Re: Photobucket

Post by Judah14 »

crfriend wrote: Nope. PNG does solve some of the compression issues because it's lossless, but nothing can mitigate the inevitable damage done when an image taken at one resolution is resized (scaled) to another.
As a pixel artist, I am very well aware of that and that is the reason why resizing pixel art PNG pictures makes editing of the resized versions difficult. If you want image formats that can be scaled easily without damage, try vector formats like Scalable Vector Graphics (SVG), though vector formats are not suitable for pixel art or photographs.
らき☆

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Caultron
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Re: Photobucket

Post by Caultron »

PNG was designs as a best-of-all-world's format, and is therefore extremely flexible. So it can use lossy compression, and most programs do that by default. Otherwise, todY's 8-, 12-, and 16-megapixel images are just too awkward to distribute.

If you have a 1920 x 1080 image and reduce it to 960 x 540, you are throwing away three quarters of its information. So if you expand it back to its original size, the image will be degraded.

Note, however, that JPEG/PNG compression is completely different than pixel resizing. They each create their own kind of degradation.
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Gregg1100
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Re: Photobucket

Post by Gregg1100 »

Just redownloaded IRFANVIEW for 64 bit puters. Tried to send a pic via email and it says I need a plugin. And there a quite a few. Which one ??
Would be a lot easier if a program came with all the gear so it could be used straight away.
Another waste of time consigned to the recycle bin.

Photobucket was ok, but riddled with sodding ads

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Sinned
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Re: Photobucket

Post by Sinned »

I've been using irfanview for years and never had a problem with it. I've posted recent photos from it and I find it easy to resize to enable to post to this site.
I believe in offering every assistance short of actual help but then mainly just want to be left to be myself in all my difference and uniqueness.

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Gregg1100
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Re: Photobucket

Post by Gregg1100 »

Like I said,
Just redownloaded IRFANVIEW for 64 bit puters. Tried to send a pic via email and it says I need a plugin. " And there a quite a few. Which one ?? ".

Plugins should be a part of the program, not an afterthought- and included with program updates. Easier all round.

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Re: Photobucket

Post by crfriend »

Hint: Don't try to use the photo-editing application to send an e-mail. Use an e-mail application to deal with E-mail.

Save the image you've been working with in the photo-editor, and then attach the saved image to a message in the e-mail application and then send that. Precisely the same thing applies for resizing an image so it'll do well here at SkrtCafe -- save the resized image in the photo-editor, exit the photo-editor, and then upload the image file using the web-browser you're using to communicate to SkirtCafe.

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Gregg1100
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Re: Photobucket

Post by Gregg1100 »

Thanks Carl---will give that a whirl.
Sinned--I wasn't being funny- it's just my age- us oldies tend to want to go straight through a problem, and not skirt around it. I found photobucket easy, but it has ads covering it like a rash. Irfanview is like VLC- so much hidden- can't really get into that, so use Windows Media Player to play my music.
I downloaded the Fall Edition of Win 10--it screwed up my resolution on monitor, and would not let me use the correct one, so I went back to previous build. I just want to browse a bit, a few forums looked at and a bit of music. Amazon and Ebay included.
Thanks for input, all.

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