300 DPI Myth | What Are DPI, PPI & LPI | Printing for Photographers
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- เผยแพร่เมื่อ 19 พ.ค. 2024
- What is the 300 DPI Myth? What are DPI, PPI and LPI? John Ross will explain to you the differences between Dots Per Inch, Pixels Per Inch, and Lines Per Inch. You will learn how to use them to supply images for Print magazines.
0:00 300 DPI Myth | What Are DPI, PPI & LPI | Printing for Photographers
0:57 PPI - Pixels Per Inch
3:45 DPI - Dots Per Inch
6:03 LPI - Lines Per Inch
8:42 The 300 DPI Myth
9:49 Finance on a Budget
𝗣𝗮𝗿𝘁 𝟭: 𝗧𝗵𝗲 𝟯𝟬𝟬 𝗗𝗣𝗜 𝗠𝘆𝘁𝗵 - 𝗗𝗣𝗜, 𝗣𝗣𝗜 𝗮𝗻𝗱 𝗟𝗣𝗜
• 300 DPI Myth | What Ar...
𝗣𝗮𝗿𝘁 𝟮: 𝗕𝗶𝘁 𝗗𝗲𝗽𝘁𝗵 𝗮𝗻𝗱 𝗧𝗼𝗻𝗮𝗹 𝗥𝗮𝗻𝗴𝗲
• What is the Bit Depth ...
𝗣𝗮𝗿𝘁 𝟯: 𝗥𝗲𝘀𝗼𝗹𝘂𝘁𝗶𝗼𝗻
• What is Effective Reso...
𝗣𝗮𝗿𝘁 𝟰: 𝗖𝗼𝗹𝗼𝗿 𝗠𝗼𝗱𝗲𝘀 𝗮𝗻𝗱 𝗖𝗼𝗹𝗼𝗿 𝗣𝗿𝗼𝗳𝗶𝗹𝗲𝘀
• What are Color Profile...
𝗗𝗶𝗴𝗶𝘁𝗮𝗹 𝗙𝘂𝗻𝗱𝗮𝗺𝗲𝗻𝘁𝗮𝗹𝘀 𝗣𝗹𝗮𝘆𝗹𝗶𝘀𝘁
• Digital Fundamentals
𝗪𝗲𝗯𝘀𝗶𝘁𝗲: www.TheArtofRetouching.com
𝗙𝗮𝗰𝗲𝗯𝗼𝗼𝗸: / theartofretouching
𝗜𝗻𝘀𝘁𝗮𝗴𝗿𝗮𝗺: / johnrossphoto
𝗙𝗶𝗻𝗮𝗻𝗰𝗲 𝗼𝗻 𝗮 𝗕𝘂𝗱𝗴𝗲𝘁: / @financeonabudget
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Been in the printing business for over 30 years, this is the most concise and clear video in this subject matter I´ve ever seen. Thank you!
Admirably clear, concise and complete. I truly salute you! ...If only all clarification videos were of this exceptional quality! Liked and subscribed!
I learned to print on a Heidelberg in Vienna/Austria when I was 16. I had to mix cmyk (HKS) on stone to match a given Color sample and dab it with my index finger on paper, transfer the Color to a plate by hand a.s.o. Long story short - i’m 50 now and I’ve seen a few things since then.
I think it‘s pretty dramatic that so many people here on TH-cam can open Adobe Photoshop but never have seen how printing machines in a printing house work but explain this topic along this stupid, confusing opening screen in Photoshop and its DPI/PPI equation.
This video is very different to those, you did a very good, high quality job.
Kids, listen to this man. He knows.
You are my new best friend, thank you for the kind words. I worked in printing for 15 years until I had enough of the overly rushed deadlines. So going into this video, I knew exactly what to say, as I've been teaching it for a decade.
But I still did my research because I wanted to ensure I covered everything in one shot, and not miss any of it. Needless to say, what I found was riddled with confusing and conflicting information. I really only came across 2 print houses that had intelligent and accurate articles.
So yes, this video stands out from the crowd.
Do they have clibrated screens? and have it checked regularly?
How close can you get to the desired colors the clients want?
Thank you i’ve had previous problems in communicating with editors and now I understand why thank you so much it’s been very informative
Man, this is the best thing ive found in my whole non-existent knowledge of printing.You'll be big soon my guy I just know it
I've already been big. It was too stressful.
This was absolutely mega, so well presented and explained - subscribed and look forward to watching and learning more!
I was once told that one of my videos was used in some Photoshop art class. But it's an old crappy video. I've long since thought this video should be mandatory for anyone getting into the printing industry. I did a lot of research to ensure everything I said was technically correct.
@@TheArtofRetouching i really need a photoshop tutorial but obviously a more up to date one, any you would suggest?
This was a very clear and informative video - well done!
thanks for the tip this helped me understand halftones better with screen printing
I change the 240 DPI value in the beginning (from raw to whatever file I need) regarding the end result, the final purpose of the image. But regarding that most commonly I work with 300 DPI or PPI because that allows me to edit the image in a way that it will not be noticed once it is printed.. Most interesting video, well explained sir!!
Education is forever changed. Thank you so much💯
Your video is everything…just saved me from purchasing a 6400dpi scanner! I’ve been watching vids that say ALL artists need 6400x9600 scanners, nothing less…they don’t explain why and they don’t mention the print factor, paper type, and the reso of the printer! Thank goodness I found this video, thank you!
Don't get pulled into the Scanner trap. My guess is that you were looking at the Epson v500 or similar. While I'm quite sure it's a very fine scanner, please ignore the specs. While technically true, they are still a lie. 48-Bit only means 16-Bit (Red, Yellow and Blue 16x3=48). 6400DPI would likely only be B/W line art, but even that has a real-world cap of like 2400DPI, if not 1200DPI depending on the Line Screen. It's a great idea to buy a v500 or v800, but only if you plan on scanning transparencies. Otherwise it's likely a waste of money. Desktop Scanner tech seems to have maxed out like 25 years ago.
Thank you so much for this explanation!
Thank you! Be sure to take a look at the videos I've released after this one. They all are part of the same Digital Fundamentals series, and each is a wealth of information.😄
A very useful information. Thank you!
Dude your videos are so clear and informative
I appreciate that!
Very helpful! Thank you 🙏
Literal best video about this topic
Thanks, great information
Very informative. Thanks!
Great video, thank you!
I used to use Adobe’s recommendation 1.5x the PPI to the screen ruling so a typical photo magazine printed at 133 LPI only really needs a 200ppi image. But try telling that to the client - no chance! The original 300ppi nonsense is the legacy of the first Apple LaserWriter 300DPI printer way back in the mid ‘80’s!
Really good breakdown Thanks 🏆🏆
Amazing video thank you
Thank you for the well researched! Ahh the art of printing is so different from just web design. so much to learn!!!! gaah
Thank you thank you thank you ❤🤞🏾
very informative
Thanks sir from Pakistan
Hi, can someone explain in more depth what he is talking about at 5:45? He says the InkJet look at the information of the PPI, not the DPI/LPI. So when I am creating my files in Photoshop, I would be using what for my resolution if I wanted a clear image? For example, an A4 size paper that is printed from a standard machine like InkJet. This information is a bit new to me, thanks for the help!
Thank you👏 👍
Excellent and very well explained information. And, yes. I change the PS 240 ppi to 300 ppi for EVERY photo edit.
Значи, човек кида.
Really a great video for the 300DPI myth! Seems this is the ONLY TH-cam video which gives us the correct answer ! But I still have a question about photo printing here: if I have a 7200X10800 pixel file with 300PPI, which people say its good for a 24X36 in print (actually I am not sure if its good enough or overkilled), can I use this file to make a 4X6 in print, and get a better, same or worse print than that big one? Will the printer automatically reduce the pixels (because of too many pixels ) to match the small size, or do anything else? Thanks.
wonder what happened as he just stopped posting!?
Very useful video ℹ️ℹ️. Very useful information ℹ️
top, parabéns vou fazer um vídeo sobre isso aqui no Brasil.
Thnk you I'm looking for info how many PPI I need for A2 Prints. I got 12,16 and 36 Mpix camera and saving for a 45 mpix D850
Great info
Nice!
this guy is genius..enuf said
Sir which photo paper is best for human portrait for 300ppi, 1:Mettalic 2:glossy, 3: matte.
Thanks for this very informative video💞💕
This is always highly subjective per-person. For me, i have always used Luster, which is between glossy and matte, with added paper texture. Like the old Kodak film days.
@@TheArtofRetouching thank u very much
9:08 wow I really took the time to pause the video just to laugh, that was funny
You forgot ink weight and how that is also very important and is governed by the quality of the stock you are printing on. Newsprint is typically 230-240% total ink weight at #100. Magazines can go up to 300% or more. You also forgot to mention dot gain which goes back to the quality and type of the stock you are printing on. The rule of thumb is what ever the screen ruling of the paper or magazine is being printed at you double the ppi of the image being supplied. This is only true for images that are being reproduced at same size or smaller than the psychical dimensions of the image file usually measured in millimetres, not pixels. When an image is enlarged its ppi reduces and therefore its reproduction quality degrades. Enlarge it too much and you get to see the pixels it's made of. Conversely if you reduce an image its ppi increases. Please note that all of this is being done with in an industry standard page makeup piece of software like Adobe Indesign or Quark Xpress.
whats the difference btw a 2510 vs 5020 LPI Graphic Tablet? Will you ever notice the difference for professional work?
You mean PPI. It means the pixels are smaller. They are selling you a higher resolution. Both sizes are fine, as you are talking about a tablet. Most likely the added pixels will do little more than burn through the battery faster. But obviously, I have no idea what products you are actually comparing.
Goos that, lad...
If you create a 1080 x 1920 file in photoshop with 1ppi & another at 300ppi. Drop a 1080 x 1920 image. In 300ppi the image is clear, but in 1ppi the image is tiny & blurry. Why so? Can anyone tell?
How to improve the dpi of an existing image? 🙏
I'm waiting for any way or method including any software.
I've been testing this lately. Topaz Sharpen AI does an amazing job at recovering lost images. However, for your very specific question of increasing DPI, the hands down winner is Topaz Gigapixel. Blow images up 6x the size to simply amazing results. I will run images through it just to get the better sharpening and face recognition. Turned a cropped 1990 1"x1" thumbnail into full sized 4x6 image. The whole lineup of software is extremely impressive.
it very much depends on the media. I print fine art and I can go as low as 182 PPI, although I tend to use 200 as a standard. Some fine art printers go as low as 120 for large prints although I think that is pressing it too much. 300 with a high quality plotter (i.e. a large Epson) is in my opinion a waste of ink.
I run a fine art reproduction shop and we print almost exclusively from 300PPI and above files, often as high as 1200PPI.
Of course it depends on your target market and price point.
Beautifully explained. Now can anyone explain why phone & monitor manufacturers are keeping secrets about what the screen is telling the device? On Windows 2000, we could set the exact number of pixels to be shown on screen, and set scaling. Now apparently users are too dumb to have the right to adjust their own screen, hence artificial manufacturer limits are in place, and worst of all, they don't publish what these limits are, so when you install android 12 or windows 10 or 11, the smallest size of icons might be WAY bigger than what you want.
As this is only an hour ago, this seems like a drunk post. While I can respect that venting, I have no idea what you are asking. I've re-read it several times. I have no idea what the question is.
So.... I ended up here because of the new Epson F170 sublimation printer. Interesting to see this
Definitely not my thing.
9:20 WHENEVER did this scenario happen? When ever I was asked for a 300DPI image in all the 20+ years of doing design, It was ALWAYS EXCLUSIVELY for the final image, most likely like a A4/A3 with bleed. If you EVER want to strech the image, you just ask for a 600DPI image from the client.
The real question is why can't we all just switch to PPC? won't that be the most logical and easy to use format?
Metric system when doing calculations is unquestionably superior to imperial which is only good if you are trading bread and goats.
Several bags to unpack here. The final version rarely, if ever, needs to be 300 PPI. We just don't print that way in USA with cheap 150LPI cover paper. Max is 200 LPI, and in 15 years I never personally needed that, at best 175LPI.
Next, I never asked for 600DPI. Maybe 1200DPI for a signature, but that was it.
Lastly, I loved your comment about imperial, metrics and goats. So yeah, I'll give you that because we used metrics in printing for many cases, though technically, not exclusively.
If anyone cares, I have 15 years of USA print experience, so I am not the usual n00b off the street.
Ok I have a question
When I have a 24 inch printer (Canon iPF GP-2000) and I print a large photo 24 inch x 36 inch
The printer have 2.400dpi and 1.200 lpi
What can the printer really print?
1200dpi = 28800 x 43200 Pixel = 1244.2 Mpx
Or
2400dpi = 57600 x 86400 Pixel = 4976.6 Mpx
Thx in advance (:
I don't know anything about that printer, so I could be wrong here, but DPI has NOTHING to do with LPI, technically. So as the advertising says 2400x1200 DPI, I suspect "Scanner" math is used, which is garbage.
There are a lot of Asterix in the copy, so it generally looks to me like marketing mumbo-jumbo. Ink-Jet printers are "scattershot", and have nothing to do with actual 4-color DPI resolutions. As such, it may be an amazing 10-color printer (overkill?), but I question the actual DPI of anything.
If you already have the printer, use a loop to zoom in. See if you have an actual pattern, or just a random mess of dots. If there is order to them, get back to me. Otherwise, DPI is garbage, and it's just a mess of dots.
@@TheArtofRetouching are there any inkjet printers you would recommend?
@@s1dew1nd3r4 I've only used Epson brand. I have an old 1400, and it still works like a champ. Canon's are OK too, but nothing else I would get involved with personally.
The PPI needs to be twice the LPI at placed size. I use 400 PPI for FM screening.
How much dpi is required to print a large size 30 feet x 20 feet billboard ?
This answer is a technical trick. Billboards are NOT printed at 300dpi. In fact, they are often closer to 50dpi because viewers are so far away, it doesn't matter. You should ask the printer the line-screen being used. I just had this come up with a client who swore she needed some 300GB sized file. I gave it to her (what do I care, I got paid), but she already had what the printer actually needed.
Aren't the real values that matter total pixels wide and total pixels high?
Well, it's "Width x Height = Total Pixels". So it doesn't matter if your camera or phone shot it, the pixel count is the pixel count. Now the actual QUALITY of those pixels is an entirely different discussion. Because as we all know, a phone of equal megapixels is still just going to smudge the crap out of the shot and be devoid of the same detail that a real camera will see.
To further refine your discussion, "AM" line screens contain "spots" of ink, not "dots" of ink. Each printed "spot" that you see in the "AM" line screen can contain anywhere from 0 to 256 printer dots. "AM" refers to Amplitude Modulation.
In my opinion, referring to "spots" inside a line screen as "dots" is equally as careless as referring to pixels on the monitor as dots.
See th-cam.com/video/8S2cnZ2QR70/w-d-xo.html for a full explanation.
I was in Printing Prepress (eventually manager) for 15 years. No matter how much I know and put into my videos, professionals that know way more than I do always show up to correct me. Can't say I've ever heard of Amplitude Modulation, as It didn't come up in daily usage (though I likely knew of it, just not a naming convention), much less spots vs. dots. After clicking your link, it appears I've already watched your video (likely 4+ years back when I was researching this one). I love when people come out to correct me, as that just gives me more information to research. Always makes me wonder though, when enough is enough knowledge? My GrandParents moved 5 hours away from the rest of us. I remember once, after 2.5 hours, asking why this wasn't far enough; only to double the driving time. I don't remember my GrandFather's answer, but when it comes to these videos I often just say "yeah, that's far enough". Thank you for your comment though. I am actively rebuilding my website and it's videos, and will likely add your comments to a new add-on video.
@@TheArtofRetouching Hi John. Thank you for your gracious reply. I'm a bit of a "stickler" for terminology. Yesterday, I noticed that in one of the dialog boxes in their latest edition of Photoshop Elements 24, Adobe mistakenly refers to image resolution in dpi, rather than ppi. My wife had to call 911.🥴
صوره رقميه 1076 في 830
كم نقطه تحتاج 300
I've been submitting stills of my film to film festivals that I've entered, and they will invariably request that they be 300 dpi. As explained in the video, they really mean 300 ppi. But this is moronic for a second reason as well: They don't specify how big they intend to print the image. I have a poster that can be printed at 24 x 36 inches, and thumbnails that could be used in a brochure or program, printed at 1 x 2 inches. Both are 300 ppi, but obviously the poster is composed of far more pixels. Requesting a 300 ppi image - even if you use the correct initials - is useless unless you also specify the size it needs to be printed at.
You are asking all the correct questions. If you check a followup video to this one, it goes into the same detailed depth about Effective Resolution. It should explain to you what you need to do, and that is going with the largest possibly used size. In your case, 24x36" for the poster. It's still 300PPI, just the number of actual pixels used is more than a thumbnail, for example. Part of the video explains it like a brick patio made out of 1000 bricks. It doesn't matter what shape the patio is, just the fact that 1000 bricks are being used is the important part. Check the video: th-cam.com/video/mnO_GpqUBII/w-d-xo.html
Pls clear my confusion
If I want to print in 300 dpi but my printer is printing in lpi then how many dpi equals lpi?
DPI would be good up to the printing LPI. This means that as long as you send 300DPI at full size, then you can print up to 300LPI (almost unheard of). But if the front cover is 150LPI (Common) then you can send 150DPI (or PPI) as long as your image is printed at 100%. If they only want to use a small part of your image (cropping in), then you want to send the 300 DPI/PPI to compensate.
@@TheArtofRetouching I am still confused if you make detail video and send link it would help very much
What's you're favorite printer bro? Laser not inkjet because if the ink spread
thank you sou saved my giant eexam
He said a couple of times that raw files are not made up of pixels. This is confusing. Strictly speaking, image files contain 1s and 0s which describe the pixels in the image. Most people would therefore say that they *contain* the pixels. So, *how* are they not made up of pixels ?????
Oh, before anyone answers... I'm not a novice. I understand at least a couple of different image file formats.
Pixels are used to display an image on a digital device. In order to view the image on the back of the camera, the information needs to be converted into pixels, and then have a color profile assigned to it. As the camera itself does not need to view the image, it does not use pixels to create or store the raw information. Think about it like this: Let's say you want to make a curved line in Photoshop. So you take the Pen tool, click two points, and drag down on the mouse. This will give you a Vector Curve. Vectors are math based algorithms. All the computer cares about are the coordinates for the first point, coordinates for the second point, and the degrees of the arc. It wants to know the RGB breakdown of the color and the thickness of the line. The computer will take that information
and create for you a Pixel based curved line. The computer does not care about the pixels, it just wants the math.
@@TheArtofRetouching i think you are very confused. Vector files (like SVG) are very different from image files (like PNG). Vector files (as you say) store coordinates. Image files store an array pixels. A digital camera converts light into an array of pixels and this is how it's stored.
@@lqueryvgOK fine, I'll complicate my answer. Raw files are unprocessed data from the camera's sensor. They are converted into pixels from demosaiching, which interprets the color information. I can make it even more complicated by including photosites and how different cameras have escalating bit-depth. But people like simple answers. Raw is malleable data, while pixels are more limited.
@@TheArtofRetouching Thanks, I've learnt some more about about raw image formats :-)
It could be argued that raw image files store pixels for each colour value but that's down to semantics.
For practical purposes, most people don't work with raw image files (e.g. when taking photos on their phone) because they'll never resample and it'll be better for them to save space instead.
It looks like you are specifically speaking to digital camera enthusiasts so I'm happy to concede the point.
@@lqueryvgYes, I am refering to actual digital cameras. I've found on my phone (on my android at least) RAW Apps allow for greater manual flexibility, but ultimately fall very flat as the screen display rarely matches the file I find when I get back home. The true benefit of RAW files are the abilty to save over or under exposed images. The benefit of digital over phones is that phones compress the crap out of the pixels, and it often looks like mush by comparison.
Terms like "2K" and "4K" don’t refer to specific resolutions. They are resolution categories. They are used to classify resolutions based on horizontal pixel count. "2K" refers to resolutions that have around 2,000 (2K) pixels horizontally. Examples include:
1920 × 1080 (16:9)
1920 × 1200 (16:10)
2048 × 1080 (≈19:10)
2048 × 1152 (16:9)
2048 × 1536 (4:3)
All of these are examples of 2K resolutions. 1920×1080 is a 2K resolution. 2048×1080 is another 2K resolution. 2560×1440 is not a 2K resolution, it is a 2.5K resolution.
"2.5K" refers to resolutions around 2,500 (2.5K) pixels horizontally. For example:
2304 × 1440 (16:10)
2400 × 1350 (16:9)
2560 × 1080 (64:27 / ≈21:9)
2560 × 1440 (16:9)
2560 × 1600 (16:10)
All of these are examples of 2.5K resolutions.
As incredibly complicated as he made it, he seems correct. 2k is "around" 2,000 pixels wide. Just as 4k is "around" 4,000 pixels wide. It more or less depends on the aspect ratio as for the exact numbers... It's complicated.
@@TheArtofRetouching "As incredibly complicated as he made it..."
What an amazingly arrogant response to a perfectly clear, very useful correction of your factual error.
@@KS0stli >blank stare< .... and you wanted me to include all that in an otherwise already complicated video? TH-cam wants quick and easy answers. I have another video that goes into the concept of pixel resolution being fluid. This is exactly what we are debating now.
@@TheArtofRetouching I did not imply any such thing. Present your videos however you want, but it might be a good idea not to publicize glaring inaccuracies (without any qualification), such as the one kAmAL pointed out above, if you want to be considered competent and trustworthy.
🙏♥️
boom math!!
so its 300 ppi because peoples images are always cropped in half for magazines ?
Not quite. It's so that if designers want to blow images up, they can easily go to 200% without any quality degradation. This is, of course, based on a standard magazine with 150 line screen cover. National Geographic prints covers at 200 line screen, so ideally the quality should be even higher. However, this explanation falls into my other video on Effective Resolution, which can make all this even more confusing. th-cam.com/video/mnO_GpqUBII/w-d-xo.html
@@TheArtofRetouching Just now seeing this video a year late. The explanations were very clear to me until you started to explain the DPI myth at 9:10 in the video. On the off chance that a designer wants to use a different crop determines the DPI makes no sense to me. Let's say the designer never changes the crop-then why is the 150DPI not appropriate for the 150LSI??? I'm not trying to be clever, I really want to understand your point.
@@DavidSmith-oi7nk 150PDI is fine for 150LSI. You got it. The assumption is that the photographer didn't crop in tight enough with the camera, so the designer does. You may send in photo at 300PPI, the designer blows it up 200%, you still have the basic 150LPI need covered. That's all there is to it. Adobe uses 240 PPI as a baseline, because even they know 300ppi is really higher than you need, especially with the large camera sensors of today.
So, you use 300 ppi just "in case" the printing side wants to scale it?
That is 100% Correct. If it is guaranteed that it will be cover printed at 150dpi with no re-sizing, then 150ppi is good. Interior magazines would make 133ppi perfectly acceptable, at 100% Effective Resolution. I have a separate video that covers that topic. I have 15+ years of magazine printing experience. I know what is needed.
@@TheArtofRetouching why do you keep saying “printed at 150 dpi”? The printing press doesn’t lower the dots per inch because the digital resolution changes. You can provide a pixelated 150px x 150px digital file, enlarge it, and the press will still print at 300 dots per inch. You’ll get a crap image because the resolution is bad. Not because the dot coverage changed.
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At 9:22 You’re contradicting yourself. You just explained how PPI is not DPI, then you’re contradicting this by stating that it is. What you mean is that the DPI, even at a high number is resampling whatever file you provide. So blowing up (enlarging) a digital image means you’ll start to see pixels - this is because the high DPI is just showing what is given. In this case a close up of the pixels.
9:25 is also wrong! Even if your digital image is blown up to 150 ppi, it would still print at 300 DPI. But it is now a clear print of a pixelated image. The PRINT quality isn’t going down. The digital resolution only does. And this can look terrible. But the printing press isn’t changing.
Super! Subscribe+
The answer presented tp the question is wrong...
300 DPI/PPI/LPI and whatever thing that you use per inch is the point at which it becomes indistinguishable to the human eye and you need to start using tools to magnify to see the difference. This is not 100% true as different people have different limits but its the reason you want to work with 300dpi, because going under means you are losing sharpness and such and going over means you are wasting resources.
"That's not how raw files save those images" is a random statement, repeated, and doesn't belong as you never explain what raw images use. As far as i know they do use pixels/dots and the distinction between the two is really mostly semantic and not worth spending 5+ minutes on.
Using TV/Screen resolution here is a real mistake because those resolutions are set, which is why SD/HD/4K all have optimal ranges because as the size of the TV/Monitor changes so to does the DPI/PPI. Ideally you want 300 PPI, but most screens have around 72 to 100 PPI. But because resolution in monitors is disconnected from the idea of resolution when scanning/printing it's really a bad thing to bring up.
WHAT? LOL!
WRONG, WRONG, WRONG! The 300 PPI is demanded for the OUTPUT (PDF) *not* the input image, so AFTER any scaling you would do.
300 PPI is ACTUALLY chosen because of the 'quality factor'. You see, If you put a picture in a digital magazine it is never EXACTLY 150 ppi (or whatever screen value you're using on a press). So, it will be something in that range, say 148, 149.5 or 150.958323. And even if it is exactly 150 PPI, changes are great it is NOT perfectly aligned with the screen of the CTP or press. And what do you get when you have two screens that do not match up EXACTLY? Moiré, a.k.a. interference patterns. The digital information will not translate evenly to the physical plates.
What do you have to do to prevent this? Make the screen really, really different, like 1.5 to 2 times higher. THAT'S how we get 300 PPI: the screen resolution (say 150) times the quality factor (ideal 2, higher values are pointless) equals 300. The lowest value is 150 * 1,5 = 225 and the in-between value is 250, the value Adobe has set as default, as a compromise.
BOOOOMMMMM, Math!
P.S.: I read this in a document by AGFA on printing and scanning in the nineties, they figured this out way back then. You've been doing it wrong for over 15 years, sorry man!
When you’re working in a program like InDesign or Illustrator, and you’ve inserted an image that is lets say 4,000 pixels by 4,000 pixels, you might scale the image down and then it becomes say (for example) 600 ppi (because all of the digital information is still there). The really high 600 ppi in your working file remains. But once you export the PDF it would then reduce the PPI to 300 (by default, unless you tell it not to). Scaling that PDF up, then of course reduces the PPi even further.
So he didn't explain what is ppi and dpi:/
Huh? I don't think you actually watched the video. That or your ADD had you skipping around looking for instant gratification.
alot of unnecessary info
I used to use Adobe’s recommendation 1.5x the PPI to the screen ruling so a typical photo magazine printed at 133 LPI only really needs a 200ppi image. But try telling that to the client - no chance! The original 300ppi nonsense is the legacy of the first Apple LaserWriter 300DPI printer way back in the mid ‘80’s!