Mobile Photo to PDF Pre-Processing: Cropping, Lighting, and Resolution

Take a photo of the file with your phone and then transfer itPDF, is the most common operation-- receipts, documents, contract page. But the same mobile phone, someone transferred it outPDFYes2MB, someone is25MB, the look is even worse. Gap in taking photosPDFPrevious pre-processing. This is a step-by-step walkthrough of each session.

Session 1: Lighting - Hidden Variables that Determine Post-Compression Rates

A lot of people don't know,Evenly-lit photos, smaller after compressionThe reason is simple.JPEGThe principle of compression is"Compress Flat Area", the color block of the uniformly lit picture is smooth, and the compression efficiency is high; when the light is dim or shaded, the picture produces a lot of noise and light and dark transitions, which"Detach"will cause the compressed volume to skyrocket.

Practical advice: try to avoid natural light by the window during the day; avoid shadows caused by overhead lights; do not turn off the flash (close proximity will reflect light resulting in high contrast noise).

Session 2: Resolution - Enough is Enough

Phone main camera4800Megapixel started, and the document was purely a cattle knife for killing chickens. Ideal document photo resolution is long edge1500-2000Pixels - Corresponding150dpiThe print quality on the left and right is more than enough for screen reading. Two control methods:

one isUse zoom when shooting, stand closer, zoom a little, so that the document is full of pictures. The fewer invalid backgrounds (desktop, floor), the higher the pixel utilization; second,TransferPDFCrop in gallery before, cut out the corners of the outside of the document to protect privacy and directly reduce the total number of pixels.

Session 3: Color Mode - Ticket Voucher to Grayscale

Black and white text is meaningless when photographed in color.PDFBefore using album editing or shortcut instructions to turn the picture to grayscale (black and white text can even be converted to pure black and white), volume reduction60%Above. There are only two scenarios that retain color: color stamps, color charts.

Session 4: GeneratePDFTool Selection

When the order is right, the tool is simple:iPhoneUse Scan Documents or the shortcut Resize→ ProductionPDF”; for AndroidAdobe Scan、WPSthe "Photo RoutePDF", they both automatically do edge recognition and resolution control. The most taboo path is to" directly take a→ photo album and choose to→ share and→ store it asPDF"--The original picture is packaged as is, and all the pretreatment in front is done in vain.

String Parameter Template

Give a brainless version: natural light+Document Full Screen→ Crop Edge→ to Grayscale→ Quick Instructions Press to1500pxBuatPDF. Test yourself10Page file stability is controlled in1.5MBWithin, the text can be searched clearly.