How does one get the very best image quality on Purpleport? I am Totally confused!

Some will say it's irrelevant, but I always use 132ppi and set the max width to 900 pixels so it matches the site's style script size.  132ppi is the screen res of my tablet and turns out to be spot on for all PC and Mac formats on any desktop resolution.  It used to be that 72ppi is enough, but you can still do that too. I find that if the ppi isn't optimal, flicking back and forth between windows showing the exact same image but at different resolutions will show alias artifacts and softer details where sharpness is paramount.

Watch out for 8bit JPEG vignette stripes and colour fade banding.  If so, save as 16bit JPEG instead and before editing.

Jon Dow said

Some will say it's irrelevant, but I always use 132ppi and set the max width to 900 pixels so it matches the site's style script size.  132ppi is the screen res of my tablet and turns out to be spot on for all PC and Mac formats on any desktop resolution.  It used to be that 72ppi is enough, but you can still do that too. I find that if the ppi isn't optimal, flicking back and forth between windows showing the exact same image but at different resolutions will show alias artifacts and softer details where sharpness is paramount.

Watch out for 8bit JPEG vignette stripes and colour fade banding.  If so, save as 16bit JPEG instead and before editing.

If it was anyone else I would think you were joking. But again this is just not true. ppi or dpi is totally irrelevant to how an image is displayed on a website/screen. It's like saying that the distance between two places is dependent on the speed you travel.

How can you save jpgs as 16bit ?, or are you just talking about using 16bit for editing prior to creating final  8bit jpg (which would make sense)

Stolenfaces said

Jon Dow said

Some will say it's irrelevant, but I always use 132ppi and set the max width to 900 pixels so it matches the site's style script size.  132ppi is the screen res of my tablet and turns out to be spot on for all PC and Mac formats on any desktop resolution.  It used to be that 72ppi is enough, but you can still do that too. I find that if the ppi isn't optimal, flicking back and forth between windows showing the exact same image but at different resolutions will show alias artifacts and softer details where sharpness is paramount.

Watch out for 8bit JPEG vignette stripes and colour fade banding.  If so, save as 16bit JPEG instead and before editing.

If it was anyone else I would think you were joking. But again this is just not true. ppi or dpi is totally irrelevant to how an image is displayed on a website/screen. It's like saying that the distance between two places is dependent on the speed you travel.

How can you save jpgs as 16bit ?, or are you just talking about using 16bit for editing prior to creating final  8bit jpg (which would make sense)

Look here, Stolenfaces, do you go through my Group posts just to have a pop every time?

I know what works well for me, on many different computers, screens, etc.  And I can see the difference.

And yes that's what I meant re the JPEG 8/16 bit. 

For everyone else:

I remember last year, someone added a comment to a similar thread stating that there were no differences between the same photo presented on a website demonstrating this very thing.  All images were shown at the same physical size on the web page's style-sheet object box.  But they varied in resolution and image size.  So I decided to sample all the images and layer them on PS.  Then it was so easy to see the differences between layers, just by turning them on and off.  Some had more aliasing, others had more jpeg artifacts and colour banding.  And that's that, really.

Edited by Jon Dow

Jon Dow said

Stolenfaces said

Jon Dow said

Some will say it's irrelevant, but I always use 132ppi and set the max width to 900 pixels so it matches the site's style script size.  132ppi is the screen res of my tablet and turns out to be spot on for all PC and Mac formats on any desktop resolution.  It used to be that 72ppi is enough, but you can still do that too. I find that if the ppi isn't optimal, flicking back and forth between windows showing the exact same image but at different resolutions will show alias artifacts and softer details where sharpness is paramount.

Watch out for 8bit JPEG vignette stripes and colour fade banding.  If so, save as 16bit JPEG instead and before editing.

If it was anyone else I would think you were joking. But again this is just not true. ppi or dpi is totally irrelevant to how an image is displayed on a website/screen. It's like saying that the distance between two places is dependent on the speed you travel.

How can you save jpgs as 16bit ?, or are you just talking about using 16bit for editing prior to creating final  8bit jpg (which would make sense)

Look here, Stolenfaces, do you go through my Group posts just to have a pop every time?

I know what works well for me, on many different computers, screens, etc.  And I can see the difference.

And yes that's what I meant re the JPEG 8/16 bit. 

If you look you can see that I have made several posts on this topic, and would have said more or less the same thing to anyone who posted as you did.

The first bit is wrong, and the second bit is helpful, but could easily be mis-read as saving and uploading a 16 bit JPG.

Jon Dow said

Some will say it's irrelevant, but I always use 132ppi and set the max width to 900 pixels so it matches the site's style script size.  132ppi is the screen res of my tablet and turns out to be spot on for all PC and Mac formats on any desktop resolution.

If you could please upload or link to an image that you have saved as "132 ppi", I'll be happy to disprove your theory once and for all, right here in this thread :)

I agree with Owen. Quality is is relevant to size pp limit that to 900px wide image(width here and in most digital forms isn't in terms of how we perceive the image. Its to do with the x pixels(horizontal) and the y pixels(vertical) ). A 4000px image can look the same in terms of quality if the resizing and compression is under your control, provided the viewer looks at the image at its intended resolution (and doesn't resize their viewing platform eg. they don't zoom in ).  

So pre resize you images yourself considering sharpness v gradient spread, make sure you set the correct bit depth and colour space for your image before resizing. Finally try to make sure whatever compression method you use is set to it maximum in terms of quality v size, if you can turn off options to re compress or enhance on up load do so.

I know all this but don't always do it then get puzzled at times when I rush as to why an image looks "wrong", its usually because I haven't done something in the above. 

Edited by Lightweavers

Stolenfaces said

Here's two different sizes upoloaded - Both have been resized to 900 px across the top. Both are save as JPGs. One is quality High and come in at 175kb  The other is quality Max and comes in at 628KB (both converted to SRGB).

Can you tell any difference ? can you tell which one is 4 times the file size of the other ?

If you click on each one they will open in new windows so that you can compare them easier

Edited by Stolenfaces

Good idea Stolenfaces.

Yes the top one is the better quality larger image, you can see the tonal range has suffered in the compression of the bottom image. 

skymouse said

Jon Dow said

Some will say it's irrelevant, but I always use 132ppi and set the max width to 900 pixels so it matches the site's style script size.  132ppi is the screen res of my tablet and turns out to be spot on for all PC and Mac formats on any desktop resolution.

If you could please upload or link to an image that you have saved as "132 ppi", I'll be happy to disprove your theory once and for all, right here in this thread :)

If you can prove on your own then go ahead. But do not use any of my images.

Edited by Jon Dow

Jon Dow said

skymouse said

Jon Dow said

Some will say it's irrelevant, but I always use 132ppi and set the max width to 900 pixels so it matches the site's style script size.  132ppi is the screen res of my tablet and turns out to be spot on for all PC and Mac formats on any desktop resolution.

If you could please upload or link to an image that you have saved as "132 ppi", I'll be happy to disprove your theory once and for all, right here in this thread :)

If you can prove on your own then go ahead. But do not use any of my images.

Edited by Jon Dow

Ok. On my profile here on PP is a snap of Governess Ely. The JPEG metadata includes the following.

XResolution: 72
YResolution: 72

ResolutionUnit: inches

The width of the image is 900 pixels.

I opened it up in several web browsers (Firefox, Internet Explorer, and Chrome). I have three monitors attached to my computer, all different brands and specs, and I dragged the browser window onto each monitor in turn, and measured the width using a Stanley FatMax rule. I also measured the widths of the three displays. If the browser honoured the metadata noted above, then the image should be displayed with a width of 900 / 72 inches = 12.5 inches in each case.

These are the details of each monitor and my measurements of the width the image displayed in the browser and the width of the whole display. Measurements are to the nearest 16th inch.

Monitor 1
Dell SE177FP
Resolution: 1280x1024 (native)
Width of image: 9 1/4 inches
Width of display: 13 1/8 inches

Monitor 2
Acer G226HQL
Resolution: 1920x1080 (native)
Width of image: 8 5/8 inches
Width of display: 18 5/8 inches

Monitor 3
HPZR2740
Resolution: 2560x1440 (native)
Width of image: 8 1/8 inches
Width of display: 23 1/4 inches.

These measurements indicate that the image is displayed at a size that varies from monitor to monitor and that. Of the three monitors used, none of them displayed the image at the size predicted by the hypothesis that the web browser honours the resolution-related metadata.

Furthermore, it can be seen from the above data that a 900 pixel wide image occupies 900 pixels of the screen for each of the monitors tested, which is consistent with previously published information about the behaviour of popular browsers such as Firefox, Internet Explorer and Chrome.

Conclusion: mainstream web browser ignore resolution-related metadata when displaying JPEG images.

(If my measurements need to be scrutinised for possible error, I will be happy to post photographs of my ruler held near the screens, when I have the time.)

Edited by skymouse

skymouse said

Jon Dow said

skymouse said

Jon Dow said

Some will say it's irrelevant, but I always use 132ppi and set the max width to 900 pixels so it matches the site's style script size.  132ppi is the screen res of my tablet and turns out to be spot on for all PC and Mac formats on any desktop resolution.

If you could please upload or link to an image that you have saved as "132 ppi", I'll be happy to disprove your theory once and for all, right here in this thread :)

If you can prove on your own then go ahead. But do not use any of my images.

Edited by Jon Dow

Ok. On my profile here on PP is a snap of Governess Ely. The JPEG metadata includes the following.

XResolution: 72
YResolution: 72

ResolutionUnit: inches

The width of the image is 900 pixels.

I opened it up in several web browsers (Firefox, Internet Explorer, and Chrome). I have three monitors attached to my computer, all different brands and specs, and I dragged the browser window onto each monitor in turn, and measured the width using a Stanley FatMax rule. I also measured the widths of the three displays. If the browser honoured the metadata noted above, then the image should be displayed with a width of 900 / 72 inches = 12.5 inches in each case.

These are the details of each monitor and my measurements of the width the image displayed in the browser and the width of the whole display. Measurements are to the nearest 16th inch.

Monitor 1
Dell SE177FP
Resolution: 1280x1024 (native)
Width of image: 9 1/4 inches
Width of display: 13 1/8 inches

Monitor 2
Acer G226HQL
Resolution: 1920x1080 (native)
Width of image: 8 5/8 inches
Width of display: 18 5/8 inches

Monitor 3
HPZR2740
Resolution: 2560x1440 (native)
Width of image: 8 1/8 inches
Width of display: 23 1/4 inches.

These measurements indicate that the image is displayed at a size that varies from monitor to monitor and that. Of the three monitors used, none of them displayed the image at the size predicted by the hypothesis that the web browser honours the resolution-related metadata.

Furthermore, it can be seen from the above data that a 900 pixel wide image occupies 900 pixels of the screen for each of the monitors tested, which is consistent with previously published information about the behaviour of popular browsers such as Firefox, Internet Explorer and Chrome.

Conclusion: mainstream web browser ignore resolution-related metadata when displaying JPEG images.

(If my measurements need to be scrutinised for possible error, I will be happy to post photographs of my ruler held near the screens, when I have the time.)

 

Edited by skymouse

What I was expecting was for you to make several versions of the same image at different sizes and resolutions so that I can download them all and make one PS file with each one as a layer. I would then flick back and forth and see the flicker differences, where some have better clarity than others.At the moment what you have written is just hearsay.

What people seem to be forgetting is that everyone has a different computer / Mac / phone / tablet, with different screen types and resolutions and different graphics cards. Some perform better at anti aliasing, whilst others perform better at showing images cleanly at their native resolutions (smaller image canvas size to that of the total size resolution of the monitor (eg if I use a 1920x1080 HD monitor, the image must be less than this in both dimensions).

The metadata is negligible too.  If I upload version 1 of an image which is 300ppi and 4000x6000 pixels in size (so basically a full size and full resolution image), the computer, web browser or the site it is uploaded to, has to do a lot of work to down-res the image for screen viewing.  Also, the image at 1:1 pixel ratio would obviously have to be stepped back from, by the graphics card, in order to see it all in one on the screen. Where PP is involved, it will downsize the image to 900px wide and whatever tall. PP has a good engine for this. Other sites do not. If I then upload the same image but prepare it before hand to a suitable smaller size for web viewing and reduce the resolution too, I know what I am getting and remove the unpredictable performance-based resizing by wherever it is being uploaded to.

It's no good posing with a ruler next to the actual screen in a selfie, I want to see what I have described above, so that I can compare qualities by layering them aligned, then flick on and off the layers in photoshop, so that predictably, I will witness a sea of artifacts within the flickers.

Edited by Jon Dow

@jondowlmpa - I don't understand what you mean by "down-res". If you mean scaling, this is irrelevant in PP profiles because the image is at most 900 pixels wide and is displayed without scaling. In PP threads, images wider than 720 pixels are scaled down to 720 pixels.

Jon Dow said

skymouse said

 

Conclusion: mainstream web browser ignore resolution-related metadata when displaying JPEG images.

(If my measurements need to be scrutinised for possible error, I will be happy to post photographs of my ruler held near the screens, when I have the time.)

 

 

 

The metadata is negligible too.

Good. So you agree this PPI stuff is irrelevant then.

Edit: I'll be happy to provide images for you to test. Please can you clarify exactly what you need for this.

Edited by skymouse

skymouse said

@jondowlmpa - I don't understand what you mean by "down-res". If you mean scaling, this is irrelevant in PP profiles because the image is at most 900 pixels wide and is displayed without scaling. In PP threads, images wider than 720 pixels are scaled down to 720 pixels.

 

Jon Dow said

skymouse said

 

Conclusion: mainstream web browser ignore resolution-related metadata when displaying JPEG images.

(If my measurements need to be scrutinised for possible error, I will be happy to post photographs of my ruler held near the screens, when I have the time.)

 

 

 

The metadata is negligible too.

Good. So you agree this PPI stuff is irrelevant then.

 

Edit: I'll be happy to provide images for you to test. Please can you clarify exactly what you need for this.

Edited by skymouse

Metadata is much more than resolution. So no, I do not agree that.

I'll tell you what I do.  I use an iPad 1 at weddings. If I show an image on it that is not the native resolution to the iPad screen - 132ppi, 1024pixels along the longest side (max), the image looks shit. Soft details and aliasing when scrutinized. When I load the same image up to match the screen 1:1, it looks fantastic.

I have fond that, since way back to 1997 when I started using Macs (Quadras) with big real estate graphics, and PCs with their 72ppi screens, it makes one hell of a difference if you want to see the sheer clarity of an image when presented on a screen and not on paper, to match the pixel resolution of the monitor, or at least assist the place it is going to end up, in doing the job right.

But it's fine, I don't need to see demo images. I'll stop banging my head against the same wall and leave you to it.

Edited by Jon Dow

No better than mobile phone screen quality. My phone screen is the best screen I own in terms of pixel count (2k screen) and density (over 500ppi)!

Jon Dow said

it makes one hell of a difference if you want to see the sheer clarity of an image when presented on a screen and not on paper, to match the pixel resolution of the monitor, or at least assist the place it is going to end up, in doing the job right.

Is this just a fancy way of saying that when you make a JPEG, you like it to have the same pixel dimensions as your iPad a sthis gives you the best view?

If so, how does this help the OP who is asking how THEY can obtain the best quality for images on a PP portfolio — which is going to be viewed by people using a variety of devices?

Also what has this got to do with "ppi"?

I use few Lightroom user presets to create JPGs to suit the need. Its lot easier and take the burden off you.