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Post by Bailey on Jan 16, 2019 11:32:19 GMT
At the other end of this link it says: For any newbies following this thread, for web display it matters absolutely ZERO what the resolution is set to. For example, if you have a 1000px x 1000px image and you set the width to 500px with "Constrain Proportions" ticked/checked then the output will always be a 500px x 500px image whether you set the resolution (PPI) to 72, 100, 240, 300 or any other value you like. Resolution (PPI) is totally meaningless for online display. The only thing that matters is the actual pixel dimensions (width, height). And in any case, all browsers will resize an image to suit the space allocated to it on the web page by the web page author. PPI is used to size images for print output. |
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Post by cats4jan on Jan 16, 2019 11:43:13 GMT
I wish this resolution thing would just go away. Pixel size is the only thing that’s relevant - even when printing. Divide your pixels by 300 and you will get a good idea of the largest good quality print you will get. For the vast majority of us, this is enough information to handle everything to do with photos.
I know there are more photo quality experts on this forum than other forums - but let them take this to the next level. For the rest of us, pixel size and 300 is all the info we need.
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Post by Bailey on Jan 16, 2019 11:59:00 GMT
I wish this resolution thing would just go away. Pixel size is the only thing that’s relevant - even when printing. Divide your pixels by 300 and you will get a good idea of the largest good quality print you will get. For the vast majority of us, this is enough information to handle everything to do with photos. I know there are more photo quality experts on this forum than other forums - but let them take this to the next level. For the rest of us, pixel size and 300 is all the info we need.
I'm not sure what you mean. By dividing by 300, you are actually using a resolution (300 ppi) to calculate the maximum good quality print size for an image.
Resolution (PPI) means everything when printing. In my case, dividing by 300, as you suggest, would be totally wrong since my Epson printer's native resolution is 360 PPI. I need to divide by 360, not 300. That's a 20% difference in maximum paper size for a good quality print.
I assume the "divide by 300" rule-of-thumb comes from the fact that most printers' native resolution is 300 PPI. But most, if not all Epson printers, have a native resolution of 360 PPI.
Another example why resolution ppi is very important in setting print sizes:
Say I have an image cropped to an A4 paper aspect ratio at 360ppi. If I choose "actual size" in the PSE print dialogue box, the image will fill the A4 sheet. If I then set the resolution to say 720 PPI without resampling and again select "actual size" in the print dialogue box, the image will half the A4 sheet.
So as I posted earlier, PPI is totally meaningless for online display. It's sole purpose is to correctly size images for printer output.
hth 
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Post by cats4jan on Jan 16, 2019 13:11:52 GMT
Ballpark Bailey - ballpark.
300 pixels per inch is enough information for the rest of us. I'm not referring to experts - I'm talking about the general public who just want to print a photo for their album or to give to Grandma. Hobbyists like me are making scrapbook pages and collages - the 'industry' loves 300 - scrapbook kits are built on 300 - 300 is enough info for the 'average joe'
Even if you need to know what size to upload to your Facebook page -- Just find out the pixel size needed for the website and check your photo - resize as needed. Resolution is irrelevant.
And yes, I realize that dividing by 300 does give resolution, but that was not my point. My point is - you need to think of how many pixels per inch you need ONLY when printing. Otherwise, forget about it.
There is so much confusion for the novice and middle of the road photo printing and collage designers - about the perfect numbers. Well, perfection just isn't needed for those of us who just dabble in this as a hobby.
I want to provide a simple equation for the average guy. That's all. Most of us just send the photo to the printer using default settings, so telling someone to check what resolution their printer likes is pretty useless.
And of course, this isn't sufficient for the purist. But I'm not talking to the purist. I'm trying to simplify life for the average photo editing hobbyist.
I've been printing greeting cards and scrapbook layouts and photos for 15 years using all manner of printers - dabbling with settings - really getting into the nitty gritty of the printer - just to learn. I'm pretty fussy about the end product - but I'm telling you - 300 is enough info.
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Post by michelb on Jan 16, 2019 20:52:34 GMT
I don't teach photo editing to beginners, but I think that I would ask them to discover by themselves what 'resolution' means for their own vision. That requires to get acquainted with: - pixels - dimensions in cm/in - viewing distance.
And taking the trouble to train do the necessary basic calculations.
Then to check where is the optimum resolution for their own vision (no loss of visible detail, no details that you can't see - for instance reading very smal fonts).
Different use cases:
- I am viewing on a 24" monitor, 1920 pixels wide at 60 cm. I can get nearer or farther. I can harly read the PSE user interface at 2 meters. ca 2,5 Mpix
- I can view on a 19" laptop, 1600 pixels at 30 centimeters. Not quite 2 Mpix
- ... on a tablet - on my Samsung A310 (2016), 8cm wide, 1280 x 720 pixels at 20 cm viewing distance ca 1 Mpix
or in print: - 4" x 6" (10 x 15 cm) in at common printing resolution (300 ppi or 120 ppcm) - 1200 x 1800 pixels - ca 2 Mpix. Viewed at any distance from 20 cm to 60 cm.
- A4 format (21 x 29,5 cm) at 300 ppi - 2500 x 3500 pixels - 9 Mpix - Photobook 30 x 30 cm (scrapbook format) at 300 ppi 3600 x 3600 pixels - 13 Mpix. - Poster from the same 9 Mpix photo in 80 x 60 cm, ca 100 ppi, looks very good at viewing distance > 1 meter.
To compare, my cameras range from 8 to 12 Mpix, my first Fuji in 1999 had 1.3 Mpix!
(but this is not the moment to compare the resolution in prints, displays and... sensors).
I am afraid beginners won't catch the meaning of printing and display resolution until they can judge by themselves and they are at ease with the above calculations.
(Note: it's a bit late, please correct me if some calculations are wrong... )
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Post by Bailey on Jan 16, 2019 21:13:51 GMT
In my original post I talk mainly about the misleading suggestion to set image documents to 72 PPI since the resolution an image is set to is meaningless for Web display for the reasons I posted.
If anyone wishes to search through my posts they will see I have referred to the ballpark 300 guide to determine ballpark max print sizes on several occasions.
The point I was making, especially for newbies, is that it doesn't matter at all what resolution you set an image to if it is for Web display.
Resolution is only important for correctly sizing images for print output.
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Post by Bailey on Jan 17, 2019 1:57:33 GMT
... And yes, I realize that dividing by 300 does give resolution........... ... For the benefit of newbies, this is not correct. Dividing by 300 gives a length, not a resolution!! The number 300 is actually the resolution in PPI (pixels per inch) you divide the length and/or width in pixels of an image. Some simple high school maths: Say you have an image 3000px wide. To get a "ballpark" maximum width you can print the image to is - 3000px / (300px/inch) = 10 inches So dividing by 300 results in a length and not a resolution value. Even if you need to know what size to upload to your Facebook page -- Just find out the pixel size needed for the website and check your photo - resize as needed. Resolution is irrelevant. This is exactly the point I am making, so you are agreeing with what I posted in my original post.
For any newbies following this thread, for web display it matters absolutely ZERO what the resolution is set to Resolution settings on images for web display are meaningless. The only thing that matters for web display is the pixel dimensions. Resolution is important only for correctly sizing images for printer output. |
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Post by Bailey on Jan 17, 2019 3:59:45 GMT
And taking the trouble to train do the necessary basic calculations. Then to check where is the optimum resolution for their own vision (no loss of visible detail, no details that you can't see - for instance reading very smal fonts). Your calculations are all based on a printer whose native resolution is 300ppi. In the case of Canon, HP and probably most other printers except Epson that is probably ok. But my Epson printer has a native resolution of 360ppi or 720ppi at the higher quality settings in the printer driver, so your calculations are wrong for my printer. The good news is that you would need to change only the 300's to 360. What you didn't mention though, which is important, is that all ink jet printers will resample an image that is not at the printer's native resolution to the printer's native resolution before printing. That is just the way all ink jet printers work. For example: 1. Lets say I create a new A4 sized document (297mm x 210mm) at 300ppi. The resultant document will be 3508px x 2480px 2. After editing it, I send it to my 360ppi native resolution printer to be printed on an A4 sheet. 3. The printer driver will first look at the dimensions of the image and say "Oops, I don't have enough pixels to print on an A4 sheet because the document is at 300ppi and I need 360ppi". 4. The printer driver will then first resample the image by adding pixels (upsizing) to 4210px (11.694in x 360ppi) by 2976px (8.267in x 360ppi) and then actually print it. So to avoid the printer driver having to resample my image to its native resolution and hence remove the risk of loss of sharpness etc, in step 1 I would need to create the new document at 360ppi and not 300ppi. This is one reason why resolution is important for printing. If your document's resolution is too far away from your printer's native resolution (300ppi or 360ppi) the printer will be forced to do a lot of resampling (upsizing or downsizing) which can affect print quality. |
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Post by michelb on Jan 17, 2019 8:11:22 GMT
Wrong. They are not based on any printer (even if my printer is a HP and all of my external printing services require or recommend the mythic 300 ppi). They are based on common values which will be used by most beginners, whether you like it or not. It's already difficult to be at ease with the two parameters: dimensions in pixels or in in/cm when you are using metric and non-metric data.
With beginners: The pre-requisite to master the relation between pixels and inches, and to evaluate how they can view and judge the differences in different situations by themselves. Once that is clear, the viewing distance factor must absolutely be taken into account if they want to grasp the idea of resolution. My examples should bring them to think about why common usage would make them choose the same ppi values for 4 x6 inches, A4, 12" x 12 " and poster size when commonly viewed at the same distance. Common use, but coherent?
With experienced users: You may not agree, but my firm belief is that what you are doing with photography should be judged by the personal visual effect. Even if therory tells you that more pixels, wider bit-depth, color depth are better, you'll find where your own limits are. Just be curious about how other users answer this question: "If my poster is viewed at two meters instead of one, how do you calculate the ppi to get the same visual resolution (which is an angle, not a pixels/length ratio)?
Then, you have to take into accound a lot of other factors like display or printer technology, old rules based on outdated softwares for mysterious reasons, Web sites with incoherent requirements, and data efficiency (why keep and transfer a lot of totally useless pixels?)
For instance the last efficiency factor has to be taken into account in your two asumptions: - ppi is irrelevant for display - process multiple files manages perfectly a batch of portrait and lanscape images.
Generally true, but not optimal, and process multiple files is limited.
About your explanation about default printer ppi: I challenge you to make users see the difference. True and interesting in theory, even if that does not take into account the various printing technologies.
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Post by Bailey on Jan 17, 2019 10:36:38 GMT
We'll just have to agree to disagree on this one then I have always assumed the commonly accepted 300ppi rule-of-thumb comes from the fact that most printers' native resolution is 300ppi. If anyone knows where the 300ppi value actually comes from, I am all ears.....I have always wondered. My printer's default native resolution is 360ppi and 720pppi at the higher quality settings. As I posted earlier, if I want to avoid my printer driver resampling an image not at 360ppi to 360ppi, and avoid all the potential loss of quality due to resampling, then I have to create an original document at 360ppi for the paper size I want to eventually print to and not 300ppi as most people would. If I created a document at 300ppi for the paper size then my image would be resampled by the printer driver before being printed as described in my previous example. To be honest, screen resolution of other peoples' monitors doesn't concern or interest me because I have no control over how my images look on their screens. Prints is my preferred and the main way I display my images. I have a very good quality monitor which I calibrate properly so that images look as good and as accurate as they can on my screen and then I print the ones I want to display using a custom profile for my printer.
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Post by cats4jan on Jan 17, 2019 11:14:11 GMT
This whole discussion is just what I was referring to
Newbies and hobbiests do not need any of this detailed information. You are making their learning experience unnecessarily confusing.
Say, they grab a photo off of Facebook and print an 8x10 - and the result is a blurry mess. They need only divide by 300 to find out their 300x600 pixel photo was never going to work at 8x10 inches because dividing by 300 would’ve told them they could expect to get only a 1x2 inch decent photo print.
I’m only saying - once I accepted this premise, a lightbulb went off and my digital life became simple.
Again - there is a difference between what a hobbyist and an expert needs to know to get the job done.
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Post by Bailey on Jan 17, 2019 19:05:19 GMT
Newbies and hobbiests do not need any of this detailed information. You are making their learning experience unnecessarily confusing. I am not sure you can speak on behalf of all newbies and hobbiests because your opinion is different to the feedback I am getting. There are newbies and hobbiests out there who want to learn more than just the basics. I am not a newbie but this is still a hobby for me. If anyone is not interested in this discussion I doubt they will follow it for long. |
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Post by Andy on Jan 18, 2019 2:30:32 GMT
I have always assumed the commonly accepted 300ppi rule-of-thumb comes from the fact that most printers' native resolution is 300ppi. A printer doesn't have a concept of PPI. It doesn't know what a pixel is. Printer resolution is based on DPI, which is a function of how finely it can lay ink down on paper (in the case of an inkjet printer). One pixel does not equal one dot, and I've seen nothing to tell me there is resampling going on if you print a 300ppi image on a printer with a 360dpi resolution. The printer driver is not simply saying to the printer - Hey, for each pixel in this image, produce one ink dot on the paper. And I agree with Janice - for the majority of individuals - including a large number of our members - the simple rule of thumb is sufficient to produce more than acceptable quality. |
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Post by Bailey on Jan 18, 2019 3:51:52 GMT
A printer doesn't have a concept of PPI. It doesn't know what a pixel is. Printer resolution is based on DPI, which is a function of how finely it can lay ink down on paper (in the case of an inkjet printer). One pixel does not equal one dot, and I've seen nothing to tell me there is resampling going on if you print a 300ppi image on a printer with a 360dpi resolution. The printer driver is not simply saying to the printer - Hey, for each pixel in this image, produce one ink dot on the paper. And I agree with Janice - for the majority of individuals - including a large number of our members - the simple rule of thumb is sufficient to produce more than acceptable quality. My Epson SC P600 printer has a native resolution of 360PPI and can print up to 5760 DPI x 1440DPI. I am fully aware of the difference between PPI and DPI.
All ink jet printers have a native print resolution. you will see There is more info on native printer resolution if you do a Google search www.google.com/search?client=firefox-b&q=printer+native+resolutionSee if you can post any evidence that proves anything I posted is not accurate.
I've done a bit more googling for you At www.lynda.com/Photoshop-tutorials/Defining-native-printer-resolution/103678/112447-4.html you will also see - |
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Post by Andy on Jan 18, 2019 5:14:03 GMT
See if you can post any evidence that proves anything I posted is not accurate. I'll only rephrase my comment that "I've seen nothing to tell me there is resampling going on if you print a 300ppi image on a printer with a 360dpi resolution.". There is some algorithm happening that is converting the image to the dots on the page. That said, I see only a lot of forum discussions and articles by individuals. I have no way of determining whether they are correct. - Please direct me to an official vendor source (Canon, Epson, etc.) that specifies that their printer has a fixed ppi that it uses and where they recommend that this should be factored in when printing. - Or show me any controlled study that proves there is a difference. |
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