Exporting PDF to a 32bit Greyscale Bitmap image for print.

[Ezra_Hollingsworth]

Hi All,

I am currently working on some Black and White labels for application to existing packaging.

As usual, I'm using Illustrator to create the files and then saving as a print PDF.

This is usually fine but the printer we are using for this run have asked me to supply bitmap files for print.

I have done this previously as an Grayscale 8 bit .bmp file and it has so far been fine.

My process is;

- Make a copy of the print PDF.

- open this in .AI and strip out all elements barring artwork and check marks for cutter edge & save.

- Open this new file in PS.

- Import Options set to - 300ppi/Grayscale/8bit

- Add white layer behind and merge with artwork layer.

- Save as .bmp

- Set BMP Options to Windows/8 bit

All have been fine previously but they have had trouble with the last couple i have sent (no difference in the way i saved and they are similar artworks) and have requested i send 32 bit .bmp files.

When i go to create these the option in the .bmp Options for 32 bit is greyed out.

I am not too familiar with .bmp files but as far as i can tell you cannot have a grayscale 32 bit .bmp because 16/32 bit both relate to RGB values instead of a single grey channel. Also if i manage to make my artwork a RGB 32 bit .bmp file this would then not print correct as the RGB channels would be converted to CMYK and then print from each channel rather than just the K channel.

Sorry if this make no sense or if daft question but it boils down to -  is there a way to create 32 bit grayscale .bmp images for print or have i been asked to do the impossible?

Regards,

Ez

[rob day · Accepted solution]

I would be worried about a printer who can't output PDF files with vector type and art. If they really are asking for 32-bit image files, there's a misunderstanding of the relationship of bit depth and print—no printing press running halftone screens is capable of printing more than 8-bit's 256 levels of gray. Both Illustrator and InDesign, which are the most widely used print apps, will only output or export 8-bits per channel. If the plan is to place the image file back into a page layout where more than 8-bit is not supported, the final output is going to be 8-bit

[JJMack]

I think you need to find our what they mean by 32bit.     8Bit color depth each color pixel has 24bits of data.  16bit color depth is wider smoother colors tones each pixel has 48bits of color information there are devices that support 8bit color and  other  the support more device drivers may only support 8Bit color others like Display adapter device driver may support 10bit for some color displays.  All I know about 32bit Color depth is that its used in HDR toning.   Many things do not support 32bit color depth like ACR and many  other filters etc.  It  is not surprising that an Image file format does not support 32bit color depth.  Jpeg does not even support 16bit color depth it only supports 8bit color.   I would think only layer files would support 32bit color depth.

[G_Hoffmann]

32-bit-per-pixel BMP contains always 3 channels RGB, each one with 8 bits.

The fourth channel is somewhat arbitrary, it can be used as alpha-channel.

No Grayscale-BMP with 32 bits per pixel exists.

The whole workflow is dubious. E.g. no ICC-profiles can be embedded.

Compression is possible only for Indexed Color (gray or color, 8bpp).

BMP dates back to about 1990.

BMP file format - Wikipedia

Best regards --Gernot Hoffmann

[JJMack]

The sound right 4 channel 8bit color.  32bits

[rob day]

I am currently working on some Black and White labels for application to existing packaging.

Also, are there gradients or gray values in the art, or is it literally Black & White? If the image is Black & White line art they may be asking for Bitmap mode (1-bit). InDesign and Illustrator list a Bitmap mode's Color Space as Black and White:

[Ezra_Hollingsworth]

Brilliant, At least I know its not just me going mad - I think they may have been stalling for time by asking for the impossible as the files used previously now work! MAGIC!!

Also in reply to Rob Day's second comment - There are no gradients or grey values just straight up 100%K vector.

Thanks everyone for your replies!

Ezra