best way to customize DPI for photoshop generator?

[cferrero]

I love the PS generator, I use it for almost everything and works great (most of my work is digital).

I was working on some images for a large scale printed signs, and I set them up like I always do, to use the generator, only to have all the images be generated in 72DPI instead of 300DPI, and I can't find a way to specify the DPI I want, is there even a way to do it? if so how?

thanks

Carolina

[D Fosse]

For print you use Save As.

Generator (and Export) is for web, screen and mobile devices, where ppi doesn't apply. So it's stripped from the file entirely. The 72 figure appears as a default when the file is reopened into Photoshop, which for unrelated reasons needs some ppi value.

[sarahs3974560]

We use generator for more than just web and screen assets and the old version left the resolution the same as the document, but now it is 72dpi always. Using the "save as" function requires you to save each manually which defeats the purpose we were using genrator for to begin with. It would be nice to save out everything with one click again. 

[vanfam]

I've been using the asset generator for a few years and have just realised (blindly doh!) that somewhere along the line it changed and now no longer takes on the default dpi of the document so all my print images I've been generating have come out as 72dpi instead of 300dpi as they used to (I have a ton of images for sale as printable digital files - you can imagine my heartbreak right now!!!) .   When it changed I have no idea but I use the Generator in scripts and actions I've written to save time and I'm really bummed that this has changed.   How now do I easily generate printable 300dpi images easily like I used to be able to do using the Generator?????  Do I have to manually now save every Group as a file??  💔😭😔 Devastated!!

PLEASE ADOBE !!!!!  make generator use the native dpi of the document not default to 72 .. it makes the generator useless unless you only create images for the web 😞

[davescm]

Nothing changed. Export does not include ppi. It never has, it was designed for screen images where ppi is irrelevant and additional unnecessary metadata would just bloat the file size.

Note - it does not 'default to 72', it removes ppi altogether i.e. no value is included.

Dave

[vanfam]

Ok great! So now I understand the image quality hasn't changed but as far as printing, will the missing reference to 300dpi matter to the printer? (I always thought that was important)

ie. When I look at the images in finder etc it says 72dpi so will the printer read it as 72dpi and therefore affect the way it prints or will it not matter and print as per the quality of the file anyway?  

1/. Do I need to go back and add the 300dpi reference to all the images?

2/. Is there a way to have the Generator add this with file naming or something if I were to continue using it to generate images for print (which I'd prefer to do). 

I sincerely appreciate your help and clarity. 

[davescm]

For printing PPI matters - in fact it is essential.

Supposing you have a 3000 x 2000 pixel image. At 100ppi that image will print 30 x 20 inches. At 300 PPI that same image will print at 10 x 6.7 inches. So PPI dictates to the printer driver how much to spread out those pixels.

If you are preparing images for print - don't use Export. If you do you will have to re-open and resave the jpeg to add the ppi value. That resave will impact the pixels due to the lossy nature of jpeg compression.

Dave

[Stephen Marsh]

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@davescm wrote:

If you are preparing images for print - don't use Export. If you do you will have to re-open and resave the jpeg to add the ppi value. That resave will impact the pixels due to the lossy nature of jpeg compression.

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It is for this reason that I would use ExifTool, it can update the metadata without de/re-compressing the binary image data.

[vanfam]

Oooh! I got excited and then I looked at it but it's all a little overwhelming with command lines.  I installed but had no idea where to start so I uninstalled.  Thanks anyway.

[Stephen Marsh]

@vanfam – Don't be daunted by a CLI, I'm happy to walk you through it – just send me a private message as Adobe don't really like 3rd party apps being discussed here (I have posted this info in the past in this forum and the Bridge forum as this is lacking in Adobe software). There are also GUI front ends available, which may still require you to enter the CLI stuff anyway so they just become a front-end for selecting files/folders.

As Dave wrote, just head this off by using Save As a Copy which will include the PPI metadata (and possibly other metadata that you may not want, which there are workarounds for).

[vanfam]

Thanks Stephen, I sincerely appreciate that.  Will see how I go.  Would really just love to be able to continue using the Generator as I've set up scripts & actions to do everything using it and now having to save each manually instead to avoid this.   Sigh! 😞

[Stephen Marsh]

There are Batch Actions, Image Processor, Image Processor Pro and Picture Processor and other scripts that can be used for bulk saving. Yes, Generator has it's benefits that if you wish to use then a third party tool is needed if the generated assets require the resolution info.

[davescm]

Good point Stephen.

Dave

[vanfam]

Thanks Dave, I don't specifically use export .. I was using the generator (which I guess is export in hindsight) - I wish using the Generator would give the option to choose to not strip for printing purposes and yes, I do understand resaving JPG images is not wise!  Appreciate your insight.

[Conrad_C]

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@vanfam wrote:

ie. When I look at the images in finder etc it says 72dpi so will the printer read it as 72dpi and therefore affect the way it prints or will it not matter and print as per the quality of the file anyway?

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Just stating ppi doesn’t say what the effective print resolution is. You might say 72 ppi, but that has no meaning unless you say both the height and width in pixels and in inches. If you don’t, you have only one half of the math; to see what the effective ppi resolution is, you have to state both the pixel dimensions and the physical dimensions (inches).

For example, if you have a 2400 x 3000 pixel image, and the printing company sets it up as 8 x 10 inches, you get:

2400 pixels wide divided by 8 inches = 300 pixels per inch

3000 pixels wide divided by 10 inches = 300 pixels per inch

So you see, even if the ppi value in the file is missing or not 300 ppi, it must end up at 300 ppi just because there are 2400 pixels wide divided by 8 inches. It doesn't matter whether it says 72 ppi or 6000 ppi in the file, as long as the printing company specifically lays out those pixel dimensions as 8 inches wide by 10 inches tall, the math dictates that number of pixels has to end up at 300 ppi at that physical size in inches.

Look at the pixel dimensions produced by Generator, and divide them by the print size you want in inches. If the resulting ppi value is enough, you’re OK no matter what ppi it says in the file.

Where it can be confusing is when the image does say 72 ppi, and the print layout software uses that ppi value to set the initial physical size on import. For example, if the 2400 x 3000 pixel file says 72 ppi, many print-oriented applications will say “OK, so 2400 x 3000 pixels divided by 72 ppi means the default print size is 33.33 x 41.66 inches.” Well, that size isn’t what a customer usually wants. But if the printing company is doing their job, they should say “That’s not the size the customer asked for, let’s set the physical size to the 8 x 10 inches they want,” and as we saw earlier,  if they set 2400 x 3000 pixels at 8 x 10 inches, that results in 300 ppi, regardless of the ppi metadata in the file.

Because ppi has no meaning until the pixel dimensions and the print size in inches are both stated, (assuming resampling isn’t used) a low ppi value in the file can be OK if the pixel dimensions are there to support the ppi value at the print size you actually want. An 8 x 10 inch image at 300 ppi can also be 4 x 5 inches at 600 ppi, or 16 x 20 inches at 150 ppi…because those are all the same 2400 x 3000 pixels, just stretched across different sized areas. Put another way, if you have 2400 x 3000 pixels at 72 ppi but you require 300 ppi, the math says you are OK as long as it will be printed at 8 x 10 inches or below.

[vanfam]

fantastic! thanks so much 🙂

[davescm]

Conrad is absolutely right in that 300ppi can be worked back from the physical size and pixel dimensions but there is a risk in doing it that way.

By not specifying a ppi  value, the software the printer uses will insert whatever default it uses for missing ppi , which could be any value but let's say 72ppi as Photoshop does, and the printer will need to alter the dimensions to make it work as specified. This is where the risk comes in. If they correct the physical dimensions without resampling then you do indeed end up printing your correct dimensions at 300ppi. However, if they alter the dimensions and resample, then you print your required dimensions at 72ppi and lose image information.

It depends whether you trust your printer to do the right thing. Some are  good and will do that, some will use the wrong option and your prints would suffer.

Personally, I would take the risk out of it and include ppi in the file. That way, the layout software should open the images with no correction necessary, and therefore nothing to get wrong.

Dave

[vanfam]

Thanks Dave, it just put my mind at ease for what has already been done so I'm not so stressed as I slowly go back and fix them all over time.  Going forward of course I will make sure this is working properly.  My biggest issue now is wanting to use the Generator as I've set up scripts & actions to do everything and now not being able to use Generator and having to do it all manually.   Gaah! 😞
I sincerely appreciate everyone's help!!! Thank you.