Changing 72 DPI to 300 DPI?

[motor]

This is probably a dumb question for many of you who print a lot of photos but I am putting together a local yearbook for a school and the program they are using requires 150-300 dpi for printing quality. I have sent enough pictures in before to understand that 300 dpi is the standard norm for glossy printing. I understand that and have no problem with that when I am only printing a few picts or saving the perfect picture for printing. Is there anyway to set the A700 to record at 300dpi or do I have to open all 1000 plus shots and resave them at 300 DPI on the computer? Mine says 72dpi to start every time. The program is detecting that and giving me an error sign every time I try to download picts from my camera into it warning me that the dpi quality is poor printing 150dpi minimum. I was just trying to save some time. If I open the file and then resave it under image size @ 300dpi it accepts it every time with no problem. Just to open and resave most of them is going to take days! Just thought I'd ask if there was a way to reset the 72 dpi to 300 DPI for future shots which there will be plenty


Motor

[motor]

I should be more specific "picture resolution" not exactly DPI because that could mean also the size of the picture! Sorry! Set the A700 to say 300 res instead of 72 res? Any Ideas or......... a better procedure than opening up every file and resaving it?

Motor

[Dr. Harout]

When opening a RAW file in Adobe Camera RAW, at the bottom you would see a blue line. Click on it and change the resolution from 72 to 300. And every time you'll open ACR you'll have 300 dpi.
I hope I did understand your question correctly

[harveyzone]

I should be more specific "picture resolution" not exactly DPI because that could mean also the size of the picture! Sorry! Set the A700 to say 300 res instead of 72 res? Any Ideas or......... a better procedure than opening up every file and resaving it?

Motor

You cannot change this in camera, so you will have to live with it.

The DPI is only a ratio of pixel count to finished print size. It is simply a number stored in the image file, and has no direct effect at all on the image size, or print quality. You do not need to change it on every image you open - just ignore it, and set it when you need to. It only makes a difference when you come to print, and even then any decent software you can get to tell you the DPI based on your required print size and pixel count, rather than the other way around.

[harvey]

Does the program refuse to load the file at all? If so it is completely broken.

What OS and image editing software are you using? You might be able to use actions or batch operations to automate conversion of a set of files at once.

I tried photoshop and Irfanview but they both seem to want to rewrite a JPEG at a new compression quality.

Harvey

[motor]

The program that I am designing the yearbook on is an internet based program provided by the yearbook company (by Jostons the biggest yearbook, book photo provider in North America. Sears, Walmart, JCPenny all use this same program.) The program is simple and easy to use I am teaching it to Middle School kids right now in my class and it keeps the quality of the image. (Very similar to Adobe PageMaker) It will accept ANY image it just gives me a warning that the final print will not appear high quality unless the image is imported in 150 res or above. Since I am taking so many pictures of activities, candid, group etc I take them in Raw/Jpeg. I can import them onto my computer using the raw imaging program but then I have to resave them as JPEG. The program only accepts JPEG. Doc your suggestion does work but resave them as JPEG take just as long. I don't really use the raw program often unless I am shooting something that I want high quality. Usually I shoot JPEG. To make it easy I have been just opening each picture individually in photoshop or AP2 and image size adjust them to 300 res 4x6. For the important ones I don't mind taking the time to adjust everything on photoshop. Many pictures are perfect as is though......... This is where my time is being wasted. On a couple pages I am making a collage of faces that have 80 pictures of kids faces. The light control, sharpness, and saturation isn't as important it just takes a while to open every picture and resave it as 300 res, 4x6 size. I was just trying to save time and set my camera for not so important shots to appear at 300 res. The actual size of the picture doesn't matter for I can recrop on the actual page. I have done some research on the internet and everyone has now said that you can't reset the camera. I am now just using a quicker means by using a program on the mac called "preview." You can adjust the size of the image in about 30 seconds. I use photoshop and ap2 primarily but it just takes to long to open every picture up and resave them as 300 res 4x6. Preview seems to work the fastest. I can open a batch up and click on each picture and save them. I then just save them as 6-1,6-2,....... for 6th grade, 7-1......for seventh grade etc to keep everything organized. I am going to continue to use this process but want to prepare for next year. I am open for suggestions and tips. This year I will be putting about 1500 picts into the yearbook. I plan on doing this for a while and just though I'd ask some question.

Thankyou all for your feedback and anything you can think of would be appreciated

Motor!

[harveyzone]

The program that I am designing the yearbook on is an internet based program provided by the yearbook company (by Jostons the biggest yearbook, book photo provider in North America. Sears, Walmart, JCPenny all use this same program.) The program is simple and easy to use I am teaching it to Middle School kids right now in my class and it keeps the quality of the image. (Very similar to Adobe PageMaker) It will accept ANY image it just gives me a warning that the final print will not appear high quality unless the image is imported in 150 res or above. Since I am taking so many pictures of activities, candid, group etc I take them in Raw/Jpeg. I can import them onto my computer using the raw imaging program but then I have to resave them as JPEG. The program only accepts JPEG. Doc your suggestion does work but resave them as JPEG take just as long. I don't really use the raw program often unless I am shooting something that I want high quality. Usually I shoot JPEG. To make it easy I have been just opening each picture individually in photoshop or AP2 and image size adjust them to 300 res 4x6. For the important ones I don't mind taking the time to adjust everything on photoshop. Many pictures are perfect as is though......... This is where my time is being wasted. On a couple pages I am making a collage of faces that have 80 pictures of kids faces. The light control, sharpness, and saturation isn't as important it just takes a while to open every picture and resave it as 300 res, 4x6 size. I was just trying to save time and set my camera for not so important shots to appear at 300 res. The actual size of the picture doesn't matter for I can recrop on the actual page. I have done some research on the internet and everyone has now said that you can't reset the camera. I am now just using a quicker means by using a program on the mac called "preview." You can adjust the size of the image in about 30 seconds. I use photoshop and ap2 primarily but it just takes to long to open every picture up and resave them as 300 res 4x6. Preview seems to work the fastest. I can open a batch up and click on each picture and save them. I then just save them as 6-1,6-2,....... for 6th grade, 7-1......for seventh grade etc to keep everything organized. I am going to continue to use this process but want to prepare for next year. I am open for suggestions and tips. This year I will be putting about 1500 picts into the yearbook. I plan on doing this for a while and just though I'd ask some question.

A 4x6 at 150dpi is 600 x 900 pixels.
A 4x6 at 300dpi is therefore 1200 x 1800 pixels

Assuming you are not printing the images larger than 4x6, and you are not cropping the images so that they end up smaller than 600 x 900 pixels you are fulfilling their requirements, even if the 'flag' in the image does not confirm this to the automated system. If it lets you do it then just ignore the warning messages.

If you really want to loose the messages then you can make your tweaks to the images, and then run them all through ACR using the image processor to change the setting in a batch, but I really wouldn't bother.

[AlphaDSLR]

If you are talking about the EXIF data, Sony seems to default every image to report 72dpi regardless of the actual resolution. Just make sure that the file you submit has a high enough resolution to print at 150-300dpi.

[Mike]

Motor,

It sounds like you are not shooting in high enough resolution in jpeg. What "Image size" is your a700 set to?

As Tom pointed out, for a 4" x 6" at 300 dpi the resolution of the picture needs to be at least 1200 x 1800. The dpi saved in the xref data is really immaterial.
With the "Image size" set to S and the aspect ratio set to 3:2 the picture should be 2128 x 1424 which would allow a 7.09" x 4.74" print at 300 dpi. If you crop at all, as most publishing software allows you to do, there may not be sufficient resolution.

It sounds like you are getting the warning because there is insufficient resolution for 300 dpi at the size you have it. The warning is not based on the resolution or the dpi of the original picture (jpeg) file, rather it's based on the available resolution of the resized picture in the publishing software.

When you "open every picture and resave it as 300 dpi, 4x6 size" " you are up sampling (adding more bits). Likely, this is the same thing that the Jostens' software would do. The reason you get the warning is because up sampling, done either by PS or the publishing software does not result in the same "quality" as starting with enough resolution.

Hope this helps,
Mike

[motor]

I am getting a grip on this subject area now though I must admit I don't totally understand it. I never really understood the dpi/ exif dpi data res etc. relationships or paid much attention to it. ( In photoshop I always just set the image to 8x12-300res and got good results when printing in the past) I ended up getting through all the call center computer system and spoke to an actual Josten's rep. He sent me over to a specialist and I got some answers Tom you are correct in the first posting. Ignore the error! Since this is for a yearbook, book or card production the program is designed for the general pubic. Most of the "general pubic" doesn't use DSL cameras they use point and shoot cameras. This error is also to allow the rep to know if students are uploading the pictures at to low res or not following the proper sequences when using a program to sharped, light adj etc. The error is designed in the system to automatically read the exif data to make sure that the resolution is at it's highest. I am shooting at 12mp, 2:3 ratio. My image is actually 59 1/2" x 48 1/2" large @72. The guy said that is called "poster size" picture! When the picture is resized the quality/ res will increase as it shrink. The error is only informing the general person who is shooting 4-6 MP at standard quality. Therefore if the person was to try to crop or make the picture larger the res would be terrible as I already knew this before and was also mentioned below. I have to make my image smaller no matter what because the page can only be 8x12 max. Again the average is 2x4, 3x5 and 4x6. Therefore I am way above what the requirements are needed. When I submit the final pages this is when I adjust the res if it is not at 300. The program is just recognizing the fact that the imported image is 72 dpi/res and not looking at the size of the picture. I can just download the picts for the collages and not change them to 300. As for perfect pictures it is better to resize them first and set it to 300, for every time I change the picture once it's been downloaded it decreases in quality. He said get as close to the image size I want for the final production and then resize them a touch if I need to in the program. I don't think I am saying this totally technical and correct but I now know alittle more about printing.

Thanks for the input. You all were very helpful!

Motor

[Mike]

My image is actually 59 1/2" x 48 1/2" large @72.
Motor

Motor,

Perhaps it's not important but an Alpha 700 cannot produce this resolution.

59 1/2" x 48 1/2" large @72 would be 4,284 by 3,492 pixels. The maximum resolution in 3:2 Aspect Ratio is 4272 x 2848 which would be approximately 59.5" by 39.6". The best explanation of this I've read is in Gary L. Friedman's "Complete Guide to Sony's Alpha 700."

If you are using Windows you can see the "dimensions" from windows explorer, see attached picture.

res screen shot.jpg (135.18 KiB) Viewed 7259 times

Or in PS CS4 if you open image size, see attached picture.

original.jpg (74.47 KiB) Viewed 7259 times

If you resize it in PS you change the resolution, for example 6" x 4" at 300 dpi results in a resolution of 1800 x 1200 pixels.

6 x 4 at 300.jpg (73.13 KiB) Viewed 7259 times

Hope this helps,
Mike

[Vidgamer]

I am getting a grip on this subject area now though I must admit I don't totally understand it. I never really understood the dpi/ exif dpi data res etc. relationships or paid much attention to it. ( In photoshop I always just set the image to 8x12-300res and got good results when printing in the past) I ended up getting through all the call center computer system and spoke to an actual Josten's rep. He sent me over to a specialist and I got some answers Tom you are correct in the first posting. Ignore the error! Since this is for a yearbook, book or card production the program is designed for the general pubic. Most of the "general pubic" doesn't use DSL cameras they use point and shoot cameras. This error is also to allow the rep to know if students are uploading the pictures at to low res or not following the proper sequences when using a program to sharped, light adj etc. The error is designed in the system to automatically read the exif data to make sure that the resolution is at it's highest.

But that DPI number doesn't tell you that. In fact, it's basically meaningless. It can be set to anything.

This DPI setting always bothered me. I guess it still does.

I am shooting at 12mp, 2:3 ratio. My image is actually 59 1/2" x 48 1/2" large @72. The guy said that is called "poster size" picture! When the picture is resized the quality/ res will increase as it shrink. The error is only informing the general person who is shooting 4-6 MP at standard quality. Therefore if the person was to try to crop or make the picture larger the res would be terrible as I already knew this before and was also mentioned below. I have to make my image smaller no matter what because the page can only be 8x12 max. Again the average is 2x4, 3x5 and 4x6. Therefore I am way above what the requirements are needed. When I submit the final pages this is when I adjust the res if it is not at 300. The program is just recognizing the fact that the imported image is 72 dpi/res and not looking at the size of the picture.

I'd call the program "broken" (as someone else suggested), at least when it comes to estimating resolution. Although, I'm not sure why Sony bothers to use 72 either. Perhaps we should consider them both in error.

I can just download the picts for the collages and not change them to 300. As for perfect pictures it is better to resize them first and set it to 300, for every time I change the picture once it's been downloaded it decreases in quality. He said get as close to the image size I want for the final production and then resize them a touch if I need to in the program. I don't think I am saying this totally technical and correct but I now know alittle more about printing.

Thanks for the input. You all were very helpful!

Motor

I don't know what your program is doing, but as a general rule, whenever a photo goes through some alteration, it loses a bit of quality. But as long as a program preserves all of the original pixels, it should be able to resize within a boundary without losing quality. Only if you resize and change the number of pixels should it lose quality, but it shouldn't have to do that just to change from "poster size" to "4x6". If it is losing pixels, then changing the DPI might be necessary, if it's really that broken! I never liked the way PS used DPI for the reason that it was hard to know quite what it was doing. Was it changing the DPI number or losing pixels? I always had trouble being sure. Better to only look at the pixel resolution. The true DPI isn't known until you go to print.....

Anyway, with a bit of experimentation, it sounds like you will figure out what works.

[stevecim]

I'd call the program "broken" (as someone else suggested), at least when it comes to estimating resolution. Although, I'm not sure why Sony bothers to use 72 either. Perhaps we should consider them both in error.

maybe Sony "fixed" this problem, seems like my A550 defaults to 350dpi

[harveyzone]

[quote="Vidgamer"]Although, I'm not sure why Sony bothers to use 72 either. Perhaps we should consider them both in error.
[quote]

I could be completely wrong here, as I have never bothered to check, but I read somewhere that the camera does not actually populate the DPI field in the Exif, (which is technically correct, as the camera has no way of knowing how large the image will be printed/displayed/used), but that the conversion software populates it to a default setting later down the line when it finds a blank field.

That aside, my advice to anyone would be to completely ignore the DPI setting in the Exif, and only worry about it on individual images when you actually come to print/display them (a lot of scaling, rotating, cropping and other manipulation can happen in between). Even then I largely ignore the Exif DPI entry unless I am dealling with software that insists on it being set correctly, and cannot work it out for itself based on Pixel count and output size.

[Vidgamer]

I could be completely wrong here, as I have never bothered to check, but I read somewhere that the camera does not actually populate the DPI field in the Exif, (which is technically correct, as the camera has no way of knowing how large the image will be printed/displayed/used), but that the conversion software populates it to a default setting later down the line when it finds a blank field.
....

You are right that the camera has no way of knowing what size you want to print/display at, which is why they stuff the field with a fixed number. I have no idea why they don't leave it blank, but I don't think they do.

From my small sample, most cameras fill this field with "something". Most tend to use 300dpi, and Sony tends to use 72.

In the old days, 72 was a good proxy for monitor resolution (but it isn't anymore). 300dpi is still a popular resolution for printing, and one would have thought that that would be more appropriate for photos...but maybe not anymore, with web and TV viewing so popular!