I often see statements in discussions about web displayed image quality that go something like this: "I only upload pictures at 72 dpi and 1200 pixels on the long edge, so if someone copies and prints the image it won't look as good as if it were 300 dpi."  What? Have I missed something here?  Does an image edited and saved/exported with 1200x800 pixels at 300 ppi look any different online than the same image saved/exported with 1200x800 pixels at 72 ppi? Other than the metadata regarding ppi, is there any difference in the two images at all? If so, what is the difference? If I tell my printer to print the images at 4R (4X6 inches) will there be any difference at all in how the printer creates a print from the 1200x800 @ 300 dpi image versus the 1200x800 @ 72 dpi image?
4053
I have two cameras, a 6mpix Panasonic FZ8, and 14mpix Canon A2200.  When I compare shots from two cameras, one of differences I notice is dpi number that camera reports in JPG info:   FZ8 reports dpi=72 A2200 reports dpi=180   What physical meaning can these numbers have? I am at loss for guesses.    I am fairly familiar with notion of dpi in scanning and printing. I can calculate density of pixels on the sensor of the camera. But then, the linear density of pixels on the sensor will be hundreds times larger than number above. So what, if anything, does it mean?
48787
Is there a way when exporting a .psd as a .pdf to make the file smaller?   My client always has me work in Photoshop and send them finished work as .pdf's, but they say the files are too big. These products are eventually printed out, so while I need to make the files smaller, they still need to have good quality. Everything is in CMYK mode already. I just don't know a lot about compression and changing file sizes
77181
Does anyone know the required resolution for a photograph to be used on a billboard?  Would the Canon 7D be able to provide a large enough file size to meet the requirements?
117367
I have just learned that PNG is a lossless image format while BMP can be both uncompressed or lossless format. Should there be a quality difference between these two? If not, does it mean that other lossless formats like TIFF, JPEG2000 and PNG offer the same quality as BMP?
101019
I apologize if this is the wrong stack exchange site, but I thought my question might be too specific to photo encoding for stack exchange.  I recently recovered a host of digital picture files from a dead drive and after the recovery noticed that although all the photos are the same resolution and are one of three encoding formats (jpg, png, or tif), there are drastic differences in their file sizes.  I know the efficiency of the compression can vary to a certain degree between photos, however, there are some as small as 112KB and others into the hundreds of megabytes.  With the really enormous files I was pretty confident that the recovery tools just scraped some extra data into the photo files, so I started going through, opening the photos in paint and then re-saving them and files that were up to approx 300MB were encoded at just 600KB.    It got me wondering, if I open two files in paint and they are the same resolution and each pixel is the same color (ie, they look identical), can there be other data behind the scenes I'm not aware of that paint is cutting out that is important to the image, or will the encoding on two files of the same number of and color pixels be the same and result in identical sizes?
9773
On the meta posts that collect community ads (), I see ads in two sizes, 300x250px and 600x500px.  (Everything renders the same when ads are actually used on the sites, as you would expect.)  The requirements for ads include:     The image that you create must be 300 x 250 pixels, or double that if high DPI.   I assume "high DPI" is a property of the software used to create the ads, or perhaps some "image export" property.  I'm not a graphics person; the ads I've made have usually started out as photos or similar art that I crop and scale to 300x250 using low-end software (Paintbrush on Mac, Paint on Windows, that kind of thing).  Should I be making them double size?  I haven't because nothing in my software says anything about "high DPI" so I assume it doesn't apply to me.  In a few months we'll be doing the next round of ads on my sites, and if I should be doing something different to make better images, I'd like to know.
1127
I am making my son's birthday invitation on illustrator. It looks perfectly fine until I save it for web so it will be a .jpeg so I can print it. Once it is a .jpeg it looks blurry. I am planing to print this like a photo. I have made things like this before just never ran in to a problem like this. How do I fix this so when they are printed it, it will be clear?  Just scared they will come out blurry when I print.
94220
This question is not directly related to graphic design, but I think you guys can help.  I am writing a thesis and I need to add several screenshots of the tools I have used and screenshots of web sites too. When I hit print screen my Fedora OS saves it on the my desktop folder. When I view them in the default image browser, they look fine. But when I add them in my document they are hardly legible.  I am going to print my thesis on A4 size paper at 600 DPI, color laser printer. How can I preprocess the images in Photoshop or GIMP so that they look correct? Should I make an A4 size 600 DPI image in Photoshop and gimp and then add screenshots to them and then optimize them?
123136
I do mockups and prototypes of sites and designs all the time, but I've always wondered if there is a standard size or width I should be using. Generally I'll make my document either 1024, 1200, or 2560px wide, depending on what I'm doing.  So what do you think? What is a good or standard size for this?
13584
What size images do I need for common print sizes, such as wallet size, 8x10, and 16x20?  Is there a general formula?  How could that size change if, for example, a 16x20 was printed on canvas rather than photopaper?
60779
When you export a picture to JPG you can normally choose its quality in a 1-100 scale. I like to keep a good quality but it wouldn't make sense to keep a JPG that will be almost as big as the original RAW, so is there any guideline to select a particular JPG quality for particular uses? I am mostly interested in Internet sharing and ordering prints online.
20498
I need to justify my choice of screen resolution for a website that has to run on old PCs. When did 1024x768 first become popular? Are there stats somewhere about how far back you'd have to go to find a desktop with resolution smaller than 1024x768? Failing that, anyone want to take a guess?
23399
I am trying to export images from the QGIS print composer, the exported image has a basemap that is loaded from an XML file following . The export doesn't look at all like the image I see in the print composer see below and I'm trying to understand why.   What I'm trying to do is simply make a decent looking map without obvious tiling with readable labels. Perhaps I have to use a satellite only image and remake with my own labels. The map is a HERE nokia hybrid map   This is a jpeg at 150 dpi, note the tiny labels in comparison to the screenshot at the bottom .   This is a png export at 300 dpi, which is standard for the print composer, note the labels, and tiles.    Finally, this is a screenshot of the map as it looks in the print composer with the labels readable at this zoom scale.
17393
I'm in trouble with finding a way to set DPI value of files within Blender. I have set up an automated workflow to generate image files for printing, but the volume is too high to open and change the DPI value of each image separately. (PNG for example)
65446
What's the dimensions of a presentation slide in pixels?   I'm having a hard time trying to get it right. I keep guessing and checking and it's taking too long. I googled some results and they're a bit off as well.  The other issue is that I'm using .opd format; the format proprietary to open office / libre office in windows 7.  I'm just trying to design a decent background for my presentation.
1768
This is the original image (610x405)    This is the image after applying image style (scale and crop) to 290x190.    Both image have the same aspect ration, yet there is visible quality loss on downsizing. Am I applying the right image style? What should I be doing?
120808
Let's take image A: 2560*1920 pixel image in perfect focus. Sharp as a razor. That's 5 Mpix.  Let's take image B: image A resized to 5120*3840. It's now a 20 Mpix file, but there's no new data in the image, so - using common sense - it's still just a 5 Mpix file, just "bloated".  Theoretically, one should be able gradually to reduce image B's dimensions until reasonable sharpness is detected (bringing it as close to image A as possible, although without actually comparing them at this point), and thus derive the image's "true" megapixel count: the size below which imagery is starting to lose its details.  This value could easily be used to determine the usefulness of a photo - if I shoot it slightly out of focus, I can still print it in a smaller size, and no-one will notice. Or, it could help with assessing lens or sensor quality - if a 24 Mpix camera is unable to capture an image with more than "true" 8 Mpix, then something isn't right.  So, cutting to the chase: is there a software program that does just that? Or am I doomed to writing my own?    From a comment by the OP to one of the answers:     I need to measure how much detail is my positive transparency scanner really getting, before I scan a collection of about 2000 old slides and consider it digitized. If I set it to optical 19200 dpi or something, and it keeps producing images with detail lost, equal to, say, a 5 Mpix camera, then I'll know it's bad.   This is the actual problem the question wants to solve. Everything above is about one perceived solution to that root problem.