Best Image Size For Upload

[rpcrowe]

I have been asked to upload some higher quality images to this site...



Previously, I uploaded images at 72ppi, but I have been asked for some higher quality images. I offered links to drop box, they still want higher quality images in this site.

Many of my images, from my 7D2 (after PP) fall within the 10mb maximum for upload. However, there are other images that exceed the 10mb maximum; such as this one...



What would be the best way to reduce the image to the maximum 10mb size allowed?

Keeping the image at the original size and reducing the resolution to 145 ppi will get me under the 10 mb maximum...



While reducing the size of the image to around 9 inches and reducing the resolution to 200 ppi will also accomplish this...



I can't seem to get any satisfactory answer from the site coordinator. I am prone to do the 9-inch, 200 ppi reduction, what do you think?

[xpatUSA]

The ppi value has no effect on images shown on-screen by a browser or viewer. It is a common error to think otherwise, so don't feel bad ...

The screen shots you show are of a dialog for printing, not posting for viewing on a monitor.

Probably not what you wanted to hear, sorry Richard.

Does their site have a maximum pixel size for posted images?

Posting JPEG sRGB should keep you below 10MB with only moderate compression, I would have thought.

[Manfred M]

Richard - you are looking at exactly the right place to do this but what is happening with the image is not altogether clear when you look at the Photoshop resize functionality.

First of all, Ted is 100% correct that to a very large extent the PPI value is nothing other than a scaling factor that gets ignored when you view on screen. Where he is not correct is that it is a printing dialogue; it is a scaling dialogue that is often used when prepping an image for print. It is also the dialogue you want to use to downsample (or upsample, in the case of printing) the image. BE CAREFUL AS THESE ARE DESTRUCTIVE PROCESSES THAT EITHER THROW AWAY DATA OR CREATE NEW DATA. Make sure you have the file saved and do not resave using the same file name as the original. This is what happens when the Resample box is checked.

You will need to change the number of pixels in the image. Change the number of pixels in the final image or use a percentage to do so. I will often pick one of the resample algorithms, rather than use the Automatic default setting. When the resample is done save the file as a JPEG and see if it is going to be the right size for the site; you'll have to use Windows Explorer to see how large the output JPEG is.

Try going with 4096 pixels on the long side, at Quality Level 10, to see how large a files are and tweak from there,

[xpatUSA]

Richard - you are looking at exactly the right place to do this but what is happening with the image is not altogether clear when you look at the Photoshop resize functionality.

First of all, Ted is 100% correct that to a very large extent the PPI value is nothing other than a scaling factor that gets ignored when you view on screen. Where he is not correct is that it is a printing dialogue; it is a scaling dialogue that is often used when prepping an image for print. It is also the dialogue you want to use to downsample (or upsample, in the case of printing) the image. BE CAREFUL AS THESE ARE DESTRUCTIVE PROCESSES THAT EITHER THROW AWAY DATA OR CREATE NEW DATA. Make sure you have the file saved and do not resave using the same file name as the original. This is what happens when the Resample box is checked.

Thanks for the correction, Manfred. Shows how much I know about Adobe stuff these days.

I agree 100% about the consequences and caveats of re-sampling. Since Richard is asking for better quality and is probably downsizing, this might be worth a read:

http://kronometric.org/phot/processi...%20methods.htm
.

[DanK]

You will need to change the number of pixels in the image.

Or simply save as a jpg with a bit less than 100% quality, that is, with a bit of additional compression. given what you are shooting with, that should get you under the 10 MB limit with no resizing at all.

[george013]

Richard.
I hope I'm not wrong.

1.

This is your original image. Dimensions are 3636x3960. When printed at 300 dpi you get a print of 12.1"x13.2". Excuse me for the decimal notation.

2.
In the next image you probably changed the dimensions, or the resolution. Your resolution is now 145, that's 145/300=0.48 times the original. Your image size has reduced with a same factor. The size of 3636 will become 3636x0.48=1757. The same for the other side. The size of the picture has changed for you resample the image.



3.
If they ask for a higher quality they probably mean more pixels. You're doing now the opposite. If they've limitations on the max size of the file you can only gain that by changing the compression factor. Do that from a raw image if possible.

George

[Dave Humphries]

Hi Richard,

It would be useful to know the actual PIXEL dimensions of your original images that were being 'complained about', but you didn't tell us that in the first or subsequent post.

If the aim of increasing the quality is to allow folks to see your pictures bigger/sharper on their screens (i.e. not for selling downloads or reproducing for prints), then I completely agree that you must 'let go' of the PPI concept.

Set the units for resizing to Pixels and ignore whatever figure appears in the PPI box.

I would suggest, for online viewing, that you resize all to a standard size; say 1920 x 1080 (FHD), since that's going to be right for a lot of folks screens. Where your image orientation isn't landscape/horizontal, or the width doesn't fill the 1920, I'd suggest sticking to the 1080 as the height and let the width set itself to whatever.

Don't forget to output sharpen after the downsizing, e.g. for USM; small Radius (0.3 or 0.4 px) and a fair Amount (e.g. 80 - 120%) to make fine details sharp again. If the image was noisy, you might want to increase Threshold from 1 or 2 to say 5 or 6.

Sticking to a standard height is going to make for a more consistent Slideshow experience for viewers.

If you upload a bigger dimension than their screens, their browser will downsize it (and soften it in the process), if you go too small (but at high jpg quality), consecutive images may actually vary in size on their screen, or if stretched to fit, look soft.

JPG quality: I suggest that anything over 75% (9/12) is wasted file size, each step up (e.g. to 10, 11 and 12) increases file size significantly, with in my experience, undetectable changes in viewing quality.

I also suggest that you largely ignore the 10MB figure, just go for the dimensions and quality I suggest and I expect it will fit within 10 MB.

Viewing an image, folks won't recognise the file size difference between say 5 MB and 9.9 MB, nor will they appreciate the quality difference between 9/12 (or 75%) and anything higher - those things just aren't obvious (unless comparing side-by-side, and even then it's doubtful). However, they may see dimensional changes between images in a Slideshow and potential sharpness changes, which may be the result of concentrating on aspects that don't actually matter much, or downsizing all by a set percentage from full size.

I know I've been a bit "prescriptive", but after a lot of research, admittedly a few years back now, this is what I found matters.

Cheers,
Dave

[xpatUSA]

Or simply save as a jpg with a bit less than 100% quality, that is, with a bit of additional compression. given what you are shooting with, that should get you under the 10 MB limit with no resizing at all.

Which confirms what I said in post No.2 "Posting JPEG sRGB should keep you below 10MB with only moderate compression ..."

[DanK]

As Dave said, you can forget about PPI. PPI has nothing to do with file size. It is a scaling factor for going from a file to a display.

Which confirms what I said in post No.2 "Posting JPEG sRGB should keep you below 10MB with only moderate compression ..."

Exactly. I just exported a 5DIII raw file (22.1 MB) as a JPEG at quality 92, using Lightroom's quality scale. The resulting file is 8 MB. at 100%, it's 13.5 MB.

Years ago, I saw some tests (perhaps by Jeffry Friedl) showing that small amounts of JPEG compression have negligible impact on perceived quality.

[xpatUSA]

As Dave said, you can forget about PPI. PPI has nothing to do with file size. It is a scaling factor for going from a file to a display.

Dan, I hate to dwell on it but I am hoping that by "display" you do not mean a computer monitor.

If I were to post two 1600px wide images here, one at 72ppi and the other at 1440ppi, they would both be 1600px wide at 100% on your screen ...

[Manfred M]

Dan, I hate to dwell on it but I am hoping that by "display" you do not mean a computer monitor.

If I were to post two 1600px wide images here, one at 72ppi and the other at 1440ppi, they would both be 1600px wide at 100% on your screen ...

The general recommendation I have is to set the PPI to a value that is close to your screen's default (native) resolution, which for my screen is around 110 PPI. The only time I use a different value is when I prepare (scale) an image for print. Here I set the image PPI to match my printer's native resolution of 360 DPI, using the appropriate upsample or downsample algorithms. I will sharpen the print at final print size and resolution, usually at 50% magnification (rather than 100%).

[xpatUSA]

The general recommendation I have is to set the PPI to a value that is close to your screen's default (native) resolution, which for my screen is around 110 PPI.

Unfortunately, the Sigma standard resolution is 180 ppi. Does that mean I should now somehow change that for every photo I shoot to my screen's 96 ppi?! Or is that action in preparation for some printing activity such as soft-proofing?

There must be some misunderstanding because the ppi setting does not change an image's size on my screen anyway.

[george013]

The general recommendation I have is to set the PPI to a value that is close to your screen's default (native) resolution, which for my screen is around 110 PPI. The only time I use a different value is when I prepare (scale) an image for print. Here I set the image PPI to match my printer's native resolution of 360 DPI, using the appropriate upsample or downsample algorithms. I will sharpen the print at final print size and resolution, usually at 50% magnification (rather than 100%).

I don't understand that. PPI is just a value of your hardware, the monitor. It's is just what it is.
DPI can mean a value of your hardware, the printer, but can also mean a recommendation to the printer driver to simulate another DPI setting as the used printer has. Both are totally irrelevant for screen output.

When Richard is asked for a higher quality they just mean more pixels. And a limitation of the max size of that file could be a problem with a megapixel sensor.

George

[MrB]

I admit to not having the technical know-how of some members here and I struggle to follow some of the technical answers given on the forum, but I do wonder whether this matter is receiving too much cerebral power. Camera makers (from point-and-shoot to DSLRs) often quote two variables affecting the image - image dimensions in pixels and image compression. From my Pentax DSLR an OOC JPEG of a subject with lots of detail records a file size of around 13 MB at 6000x4000 pixels and at the lowest compression (highest quality - 3 Star). Using PaintShop Pro, keeping the same dimensions but increasing the image compression by just 10% (i.e. 90% of the OOC quality), gives a file size of around 9 MB - isn't this what is being requested?

Cheers.
Philip

[Manfred M]

I don't understand that. PPI is just a value of your hardware, the monitor. It's is just what it is.
DPI can mean a value of your hardware, the printer, but can also mean a recommendation to the printer driver to simulate another DPI setting as the used printer has. Both are totally irrelevant for screen output.

When Richard is asked for a higher quality they just mean more pixels. And a limitation of the max size of that file could be a problem with a megapixel sensor.

George

My comments are relevant to the original question. I have include a comment by Ted, which is what I am responding to, rather than to Richard's original question. It also covers why one would want to change the DPI setting.

Both the printer and computer screen have a "native" resolution that is set by the pixel / dot size of those devices based on how they are built. Having an image that exactly meets those specs means that the display / print drivers do not have to do any interpolation and what we see is the highest quality as no pixels are added or removed. If we are not viewing (for editing purposes) or printing at those sizes, we are seeing an image that is not optimized. Most people probably do not care, but if one is doing large format prints and trying to get the highest quality output, it does matter.

[xpatUSA]

My comments are relevant to the original question. I have include a comment by Ted, which is what I am responding to, rather than to Richard's original question. It also covers why one would want to change the DPI setting.

Both the printer and computer screen have a "native" resolution that is set by the pixel / dot size of those devices based on how they are built. Having an image that exactly meets those specs means that the display / print drivers do not have to do any interpolation and what we see is the highest quality as no pixels are added or removed. If we are not viewing (for editing purposes) or printing at those sizes, we are seeing an image that is not optimized. Most people probably do not care, but if one is doing large format prints and trying to get the highest quality output, it does matter.

We must be talking at cross-purposes Manfred. The subject at hand is basic enough that we should be able to resolve it while we wait for Richard to tell us what was meant by "quality".

But first:

I don't print; therefore, I don't soft-proof.

I don't use Adobe products for resizing.

I only view on my 96 ppi monitor.

On my screen, the quality of an image is completely unaffected by the so-called "ppi setting".

Having said that:

You said "Having an image that exactly meets those specs means that the display / print drivers do not have to do any interpolation and what we see is the highest quality." (my bold).

What that statement implies is that any image with it's ppi set to other than the display's native resolution will not be of the "highest quality" because interpolation is necessary. Something to do with Adobe, I suspect.

I claim that your statement does not generally apply to display drivers.

Open question:

Where is the "ppi" setting found in the EXIF or other meta-data; by which I mean what tag number(s)?

[george013]

My comments are relevant to the original question. I have include a comment by Ted, which is what I am responding to, rather than to Richard's original question. It also covers why one would want to change the DPI setting.

Both the printer and computer screen have a "native" resolution that is set by the pixel / dot size of those devices based on how they are built. Having an image that exactly meets those specs means that the display / print drivers do not have to do any interpolation and what we see is the highest quality as no pixels are added or removed. If we are not viewing (for editing purposes) or printing at those sizes, we are seeing an image that is not optimized. Most people probably do not care, but if one is doing large format prints and trying to get the highest quality output, it does matter.

It doesn't happen often that Ted and I are on one line

Please, reread your post carefully.

I'm not aware of any place you can set the PPI of your image for screen display.
Viewing an image on my screen is done either at 100% meaning 1 image pixel is 1 monitor pixel or at window dimension whatever that may be. And anything more or less.

George

[xpatUSA]

It doesn't happen often that Ted and I are on one line

I'm not aware of any place you can set the PPI of your image for screen display.

Thank you George!

I just now took two equal sized images (original by Scott B Kennelly). I set the EXIF resolution to 72ppi in the one and 300ppi in the other, neither of which is my monitor's "native" resolution. Here they are:

72ppi


300ppi


Anyone see a difference on their screen?

[Manfred M]

You are quite correct Ted, your camera's sensor, your computer screen and any printer have fixed pixel sizes so their resolutions are set by the equipment manufacturer.

What I have been taught is that for most purposes, the PPI should be set to the screen display's native PPI value. The "default" value of 72 PPI comes from the analogue CRT screen days where this was in fact the default size for most any screen (I'm not sure if this was true for true studio monitors, but those things cost as much as a mid-range car); as the screen got larger, so did the individual pixels; the 72 PPI was a constant.

With the advent of the LCD display technology, this has changed as manufacturers have crammed ever more pixels into the same surface area. When I look at my 27" screen, a dimension of 23.5" on the long side and with a native resolution of 2560 pixels in that direction. 2560 / 23.5 gives me about 109 PPI as the screen's native resolution. That is what I use as a default PPI value on my screen. The only time it truly matters is when I am working at 100% magnification and am working on operations where this has an impact; sharpness adjustments come to mind here. For other global adjustments like white balance, exposure, etc. it makes no difference.

Soft proofing is really aimed at people who print as a way of emulating how the image will look like using a specific paper / printer combination. It is a tool I use a lot when deciding what paper to use to print on and to fine tune the output for printing. For someone like yourself who does not print, I suspect the use is more limited other than perhaps to identify how out of gamut colours are handled when a narrower colour space is used. Screen and printer resolution do not come into play at all here.

As I am a printer (I generally produce 3 or 4 prints a week), these things do matter to me more than to most. All of my formal photographic training was taught (and continues to be taught) by people who print and view the print as the output of the photographic process. This means I tend to have a (using your words, Ted) a more pendantic view and approach to the whole photographic process. Virtually every image I take is done with the view of producing a print down the road.

[Manfred M]

Thank you George!

I just now took two equal sized images (original by Scott B Kennelly). I set the EXIF resolution to 72ppi in the one and 300ppi in the other, neither of which is my monitor's "native" resolution. Here they are:



Anyone see a difference on their screen?

Of course not. One would not expect to either.